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Publisher: Springer-Verlag   (Total: 2355 journals)

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Showing 1 - 200 of 2355 Journals sorted alphabetically
3D Research     Hybrid Journal   (Followers: 19, SJR: 0.214, h-index: 10)
4OR: A Quarterly J. of Operations Research     Hybrid Journal   (Followers: 9, SJR: 1.073, h-index: 25)
AAPS J.     Hybrid Journal   (Followers: 20, SJR: 1.192, h-index: 74)
AAPS PharmSciTech     Hybrid Journal   (Followers: 6, SJR: 0.718, h-index: 54)
Abdominal Imaging     Hybrid Journal   (Followers: 14, SJR: 0.723, h-index: 60)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 2, SJR: 0.447, h-index: 12)
Academic Psychiatry     Full-text available via subscription   (Followers: 22, SJR: 0.492, h-index: 32)
Academic Questions     Hybrid Journal   (Followers: 7, SJR: 0.135, h-index: 6)
Accreditation and Quality Assurance: J. for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 26, SJR: 0.378, h-index: 30)
Acoustical Physics     Hybrid Journal   (Followers: 11, SJR: 0.355, h-index: 20)
Acoustics Australia     Hybrid Journal  
Acta Analytica     Hybrid Journal   (Followers: 7, SJR: 0.387, h-index: 6)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1, SJR: 0.624, h-index: 34)
Acta Biotheoretica     Hybrid Journal   (Followers: 5, SJR: 0.419, h-index: 25)
Acta Diabetologica     Hybrid Journal   (Followers: 14, SJR: 1.318, h-index: 46)
Acta Endoscopica     Hybrid Journal   (Followers: 1, SJR: 0.113, h-index: 8)
acta ethologica     Hybrid Journal   (Followers: 4, SJR: 0.465, h-index: 23)
Acta Geochimica     Hybrid Journal   (Followers: 3)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 1, SJR: 0.294, h-index: 13)
Acta Geotechnica     Hybrid Journal   (Followers: 7, SJR: 1.818, h-index: 22)
Acta Informatica     Hybrid Journal   (Followers: 5, SJR: 0.524, h-index: 32)
Acta Mathematica     Hybrid Journal   (Followers: 11, SJR: 8.021, h-index: 47)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2, SJR: 0.53, h-index: 29)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 5, SJR: 0.406, h-index: 30)
Acta Mathematica Vietnamica     Hybrid Journal   (SJR: 0.451, h-index: 5)
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal   (SJR: 0.22, h-index: 20)
Acta Mechanica     Hybrid Journal   (Followers: 19, SJR: 0.898, h-index: 52)
Acta Mechanica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.426, h-index: 29)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 5, SJR: 0.525, h-index: 18)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.524, h-index: 14)
Acta Neurochirurgica     Hybrid Journal   (Followers: 6, SJR: 0.833, h-index: 73)
Acta Neurologica Belgica     Hybrid Journal   (SJR: 0.348, h-index: 27)
Acta Neuropathologica     Hybrid Journal   (Followers: 3, SJR: 6.61, h-index: 117)
Acta Oceanologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.295, h-index: 17)
Acta Parasitologica     Hybrid Journal   (Followers: 9, SJR: 0.581, h-index: 28)
Acta Physiologiae Plantarum     Hybrid Journal   (Followers: 2, SJR: 0.551, h-index: 39)
Acta Politica     Hybrid Journal   (Followers: 13, SJR: 0.658, h-index: 20)
Activitas Nervosa Superior     Hybrid Journal  
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 5, SJR: 0.103, h-index: 4)
ADHD Attention Deficit and Hyperactivity Disorders     Hybrid Journal   (Followers: 20, SJR: 0.871, h-index: 15)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 7)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 15, SJR: 0.795, h-index: 40)
Adsorption     Hybrid Journal   (Followers: 4, SJR: 0.774, h-index: 52)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3, SJR: 0.319, h-index: 15)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 34, SJR: 0.959, h-index: 44)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15, SJR: 1.255, h-index: 44)
Advances in Contraception     Hybrid Journal   (Followers: 3)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 53, SJR: 1.113, h-index: 14)
Advances in Gerontology     Partially Free   (Followers: 9, SJR: 0.141, h-index: 3)
Advances in Health Sciences Education     Hybrid Journal   (Followers: 23, SJR: 1.397, h-index: 42)
Advances in Manufacturing     Hybrid Journal   (Followers: 3, SJR: 0.2, h-index: 4)
Advances in Polymer Science     Hybrid Journal   (Followers: 41, SJR: 0.637, h-index: 89)
Advances in Therapy     Hybrid Journal   (Followers: 5, SJR: 0.79, h-index: 44)
Aegean Review of the Law of the Sea and Maritime Law     Hybrid Journal   (Followers: 7)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2, SJR: 0.882, h-index: 23)
Aerobiologia     Hybrid Journal   (Followers: 1, SJR: 0.511, h-index: 36)
Aesthetic Plastic Surgery     Hybrid Journal   (Followers: 9, SJR: 0.821, h-index: 49)
African Archaeological Review     Hybrid Journal   (Followers: 15, SJR: 0.612, h-index: 24)
Afrika Matematika     Hybrid Journal   (Followers: 1, SJR: 0.248, h-index: 6)
AGE     Hybrid Journal   (Followers: 7, SJR: 1.358, h-index: 33)
Ageing Intl.     Hybrid Journal   (Followers: 7, SJR: 0.337, h-index: 10)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
Aging Clinical and Experimental Research     Hybrid Journal   (Followers: 3, SJR: 0.529, h-index: 55)
Agricultural Research     Hybrid Journal   (Followers: 3)
Agriculture and Human Values     Hybrid Journal   (Followers: 12, SJR: 1.197, h-index: 49)
Agroforestry Systems     Hybrid Journal   (Followers: 19, SJR: 0.64, h-index: 56)
Agronomy for Sustainable Development     Hybrid Journal   (Followers: 10, SJR: 1.732, h-index: 59)
AI & Society     Hybrid Journal   (Followers: 6, SJR: 0.171, h-index: 19)
AIDS and Behavior     Hybrid Journal   (Followers: 13, SJR: 2.006, h-index: 71)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 3, SJR: 0.706, h-index: 19)
Akupunktur & Aurikulomedizin     Full-text available via subscription   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 3, SJR: 0.566, h-index: 18)
Algebra Universalis     Hybrid Journal   (Followers: 2, SJR: 0.388, h-index: 22)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1, SJR: 0.868, h-index: 20)
Algorithmica     Hybrid Journal   (Followers: 7, SJR: 0.898, h-index: 56)
Allergo J.     Full-text available via subscription   (Followers: 1, SJR: 0.183, h-index: 20)
Allergo J. Intl.     Hybrid Journal   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 4, SJR: 0.729, h-index: 20)
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 3, SJR: 1.392, h-index: 32)
AMBIO     Hybrid Journal   (Followers: 15, SJR: 1.094, h-index: 87)
American J. of Cardiovascular Drugs     Hybrid Journal   (Followers: 11, SJR: 0.864, h-index: 39)
American J. of Community Psychology     Hybrid Journal   (Followers: 24, SJR: 1.237, h-index: 83)
American J. of Criminal Justice     Hybrid Journal   (Followers: 6, SJR: 0.634, h-index: 13)
American J. of Cultural Sociology     Hybrid Journal   (Followers: 11, SJR: 0.283, h-index: 3)
American J. of Dance Therapy     Hybrid Journal   (Followers: 4, SJR: 0.175, h-index: 13)
American J. of Potato Research     Hybrid Journal   (Followers: 2, SJR: 0.558, h-index: 35)
American J. of Psychoanalysis     Hybrid Journal   (Followers: 21, SJR: 0.293, h-index: 13)
American Sociologist     Hybrid Journal   (Followers: 12, SJR: 0.18, h-index: 13)
Amino Acids     Hybrid Journal   (Followers: 8, SJR: 1.362, h-index: 83)
AMS Review     Partially Free   (Followers: 4)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 5, SJR: 0.21, h-index: 37)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 3, SJR: 0.665, h-index: 7)
Analysis in Theory and Applications     Hybrid Journal  
Analysis of Verbal Behavior     Hybrid Journal   (Followers: 4)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 28, SJR: 1.096, h-index: 123)
Anatomical Science Intl.     Hybrid Journal   (Followers: 2, SJR: 0.301, h-index: 26)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3, SJR: 2.212, h-index: 69)
Animal Cognition     Hybrid Journal   (Followers: 16, SJR: 1.122, h-index: 55)
Annales françaises de médecine d'urgence     Hybrid Journal   (Followers: 1, SJR: 0.156, h-index: 4)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3, SJR: 1.377, h-index: 32)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annali dell'Universita di Ferrara     Hybrid Journal   (SJR: 0.504, h-index: 14)
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1, SJR: 1.167, h-index: 26)
Annals of Behavioral Medicine     Hybrid Journal   (Followers: 11, SJR: 2.112, h-index: 98)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 18, SJR: 1.182, h-index: 94)
Annals of Combinatorics     Hybrid Journal   (Followers: 3, SJR: 0.849, h-index: 15)
Annals of Data Science     Hybrid Journal   (Followers: 8)
Annals of Dyslexia     Hybrid Journal   (Followers: 9, SJR: 0.857, h-index: 40)
Annals of Finance     Hybrid Journal   (Followers: 28, SJR: 0.686, h-index: 14)
Annals of Forest Science     Hybrid Journal   (Followers: 4, SJR: 0.929, h-index: 57)
Annals of Global Analysis and Geometry     Hybrid Journal   (Followers: 1, SJR: 1.136, h-index: 23)
Annals of Hematology     Hybrid Journal   (Followers: 14, SJR: 1.117, h-index: 62)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6, SJR: 0.593, h-index: 42)
Annals of Microbiology     Hybrid Journal   (Followers: 9, SJR: 0.402, h-index: 26)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 5, SJR: 0.68, h-index: 45)
Annals of Operations Research     Hybrid Journal   (Followers: 8, SJR: 1.186, h-index: 78)
Annals of Ophthalmology     Hybrid Journal   (Followers: 9)
Annals of Regional Science     Hybrid Journal   (Followers: 7, SJR: 0.405, h-index: 42)
Annals of Software Engineering     Hybrid Journal   (Followers: 12)
Annals of Solid and Structural Mechanics     Hybrid Journal   (Followers: 10, SJR: 0.553, h-index: 8)
Annals of Surgical Oncology     Hybrid Journal   (Followers: 11, SJR: 1.902, h-index: 127)
Annals of Telecommunications     Hybrid Journal   (Followers: 7, SJR: 0.315, h-index: 25)
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1, SJR: 0.931, h-index: 31)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5, SJR: 0.992, h-index: 87)
Apidologie     Hybrid Journal   (Followers: 4, SJR: 1.14, h-index: 57)
APOPTOSIS     Hybrid Journal   (Followers: 8, SJR: 1.554, h-index: 87)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2, SJR: 0.354, h-index: 27)
Applications of Mathematics     Hybrid Journal   (Followers: 1, SJR: 0.274, h-index: 20)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44, SJR: 0.575, h-index: 80)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 17, SJR: 0.267, h-index: 26)
Applied Cancer Research     Open Access  
Applied Categorical Structures     Hybrid Journal   (Followers: 2, SJR: 0.361, h-index: 21)
Applied Composite Materials     Hybrid Journal   (Followers: 47, SJR: 0.705, h-index: 35)
Applied Entomology and Zoology     Partially Free   (Followers: 2, SJR: 0.554, h-index: 34)
Applied Geomatics     Hybrid Journal   (Followers: 3, SJR: 0.323, h-index: 9)
Applied Geophysics     Hybrid Journal   (Followers: 7, SJR: 0.541, h-index: 13)
Applied Intelligence     Hybrid Journal   (Followers: 12, SJR: 0.777, h-index: 43)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 3, SJR: 0.358, h-index: 34)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 4, SJR: 0.955, h-index: 33)
Applied Mathematics - A J. of Chinese Universities     Hybrid Journal   (SJR: 0.275, h-index: 8)
Applied Mathematics and Mechanics     Hybrid Journal   (Followers: 4, SJR: 0.37, h-index: 26)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 60, SJR: 1.262, h-index: 161)
Applied Physics A     Hybrid Journal   (Followers: 7, SJR: 0.535, h-index: 121)
Applied Physics B: Lasers and Optics     Hybrid Journal   (Followers: 23, SJR: 0.983, h-index: 104)
Applied Psychophysiology and Biofeedback     Hybrid Journal   (Followers: 8, SJR: 0.677, h-index: 47)
Applied Research in Quality of Life     Hybrid Journal   (Followers: 10, SJR: 0.288, h-index: 15)
Applied Solar Energy     Hybrid Journal   (Followers: 17, SJR: 0.251, h-index: 6)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4, SJR: 0.351, h-index: 9)
Aquaculture Intl.     Hybrid Journal   (Followers: 22, SJR: 0.613, h-index: 40)
Aquarium Sciences and Conservation     Hybrid Journal   (Followers: 1)
Aquatic Ecology     Hybrid Journal   (Followers: 30, SJR: 0.646, h-index: 44)
Aquatic Geochemistry     Hybrid Journal   (Followers: 3, SJR: 0.764, h-index: 39)
Aquatic Sciences     Hybrid Journal   (Followers: 12, SJR: 1.172, h-index: 53)
Arabian J. for Science and Engineering     Hybrid Journal   (Followers: 5, SJR: 0.345, h-index: 20)
Arabian J. of Geosciences     Hybrid Journal   (Followers: 1, SJR: 0.417, h-index: 16)
Archaeological and Anthropological Sciences     Hybrid Journal   (Followers: 21, SJR: 1.056, h-index: 15)
Archaeologies     Hybrid Journal   (Followers: 12, SJR: 0.397, h-index: 13)
Archiv der Mathematik     Hybrid Journal   (Followers: 1, SJR: 0.597, h-index: 29)
Archival Science     Hybrid Journal   (Followers: 53, SJR: 0.804, h-index: 22)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7, SJR: 0.28, h-index: 15)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 1, SJR: 0.946, h-index: 23)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (SJR: 4.091, h-index: 66)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 4, SJR: 0.865, h-index: 40)
Archives and Museum Informatics     Hybrid Journal   (Followers: 119)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4, SJR: 2.841, h-index: 40)
Archives of Dermatological Research     Hybrid Journal   (Followers: 6, SJR: 0.9, h-index: 65)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 10, SJR: 0.846, h-index: 84)
Archives of Gynecology and Obstetrics     Hybrid Journal   (Followers: 17, SJR: 0.695, h-index: 47)
Archives of Microbiology     Hybrid Journal   (Followers: 8, SJR: 0.702, h-index: 85)
Archives of Orthopaedic and Trauma Surgery     Hybrid Journal   (Followers: 8, SJR: 1.039, h-index: 56)
Archives of Osteoporosis     Hybrid Journal   (Followers: 2, SJR: 1.092, h-index: 13)
Archives of Sexual Behavior     Hybrid Journal   (Followers: 9, SJR: 1.198, h-index: 74)
Archives of Toxicology     Hybrid Journal   (Followers: 16, SJR: 1.595, h-index: 76)
Archives of Virology     Hybrid Journal   (Followers: 5, SJR: 1.086, h-index: 90)
Archives of Women's Mental Health     Hybrid Journal   (Followers: 13, SJR: 1.264, h-index: 50)
Archivio di Ortopedia e Reumatologia     Hybrid Journal  
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2, SJR: 1.2, h-index: 42)
ArgoSpine News & J.     Hybrid Journal   (SJR: 0.102, h-index: 3)
Argumentation     Hybrid Journal   (Followers: 5, SJR: 0.295, h-index: 18)
Arid Ecosystems     Hybrid Journal   (Followers: 3)
Arkiv för Matematik     Hybrid Journal   (Followers: 1, SJR: 0.948, h-index: 22)
Arnold Mathematical J.     Hybrid Journal   (Followers: 1)
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 1, SJR: 0.797, h-index: 17)
Arthroskopie     Hybrid Journal   (Followers: 1, SJR: 0.145, h-index: 8)
Artificial Intelligence and Law     Hybrid Journal   (Followers: 9, SJR: 0.288, h-index: 25)
Artificial Intelligence Review     Hybrid Journal   (Followers: 14, SJR: 0.948, h-index: 48)
Artificial Life and Robotics     Hybrid Journal   (Followers: 7, SJR: 0.231, h-index: 14)
Asia Europe J.     Hybrid Journal   (Followers: 4, SJR: 0.247, h-index: 9)
Asia Pacific Education Review     Hybrid Journal   (Followers: 9, SJR: 0.371, h-index: 17)
Asia Pacific J. of Management     Hybrid Journal   (Followers: 12, SJR: 1.676, h-index: 50)
Asia-Pacific Education Researcher     Hybrid Journal   (Followers: 11, SJR: 0.353, h-index: 13)
Asia-Pacific Financial Markets     Hybrid Journal   (Followers: 2, SJR: 0.19, h-index: 15)
Asia-Pacific J. of Atmospheric Sciences     Hybrid Journal   (Followers: 20, SJR: 1.006, h-index: 14)
Asian Business & Management     Hybrid Journal   (Followers: 7, SJR: 0.41, h-index: 10)
Asian J. of Business Ethics     Hybrid Journal   (Followers: 7)
Asian J. of Criminology     Hybrid Journal   (Followers: 5, SJR: 0.263, h-index: 8)
AStA Advances in Statistical Analysis     Hybrid Journal   (Followers: 2, SJR: 0.681, h-index: 15)
AStA Wirtschafts- und Sozialstatistisches Archiv     Hybrid Journal   (Followers: 5, SJR: 0.195, h-index: 5)
ästhetische dermatologie & kosmetologie     Full-text available via subscription  

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Journal Cover Applied Biochemistry and Biotechnology
  [SJR: 0.575]   [H-I: 80]   [44 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1599-0291 - ISSN (Online) 0273-2289
   Published by Springer-Verlag Homepage  [2355 journals]
  • Semi-Rational Engineering of Leucine Dehydrogenase for L -2-Aminobutyric
           Acid Production
    • Authors: Jian-Miao Xu; Feng Cheng; Fang-Tian Fu; Hai-Feng Hu; Yu-Guo Zheng
      Pages: 898 - 909
      Abstract: L-2-aminobutyric acid (L-ABA) as a precursor for the anticonvulsant and the antituberculotic is a key intermediate in the chemical and pharmaceutical industries. Recently, leucine dehydrogenase (LeuDH) with NAD+ regeneration was developed for L-ABA production on a large scale. Previously, the L-ABA yield was improved by optimizing conversion conditions, including cofactor regeneration and enzyme immobilization but not protein engineering on LeuDH due to lacking an applicable high-throughput screening (HTS) method. Recently, an HTS assay was developed by us, which enables researchers to engineer LeuDH in a relatively short period of time. Herein, a semirational engineering was performed on LeuDH to increase the catalytic efficiency of BcLeuDH. Firstly, the structure of wild-type (WT) BcLeuDH was modeled and seven potentially beneficial positions were selected for mutation. Five beneficial variants were then identified from the seven site-saturation mutagenesis (SSM) libraries by HTS and confirmed by rescreening via amino acid analyzer. The “best” variant M5 (WT + Q358N) showed 44.5-fold higher catalytic efficiency (k cat/K M) than BcLeuDH WT, which suggested that BcLeuDH M5 is an attractive candidate for L-ABA production on a large scale. Furthermore, the structure-functional relationship was investigated based on the docking and kinetic results.
      PubDate: 2017-07-01
      DOI: 10.1007/s12010-016-2369-0
      Issue No: Vol. 182, No. 3 (2017)
  • Enhanced Production of Poly-γ-glutamic Acid by Bacillus licheniformis
           TISTR 1010 with Environmental Controls
    • Authors: Nuttawut Kongklom; Zhongping Shi; Yusuf Chisti; Sarote Sirisansaneeyakul
      Pages: 990 - 999
      Abstract: Bacillus licheniformis TISTR 1010 was used for glutamic acid-independent production of poly-γ-glutamic acid (γ-PGA). A fed-batch production strategy was developed involving feedings of glucose, citric acid, and ammonium chloride at specified stages of the fermentation. With the dissolved oxygen concentration controlled at ≥50% of air saturation and the pH controlled at ~7.4, the fed-batch operation at 37 °C afforded a peak γ-PGA concentration of 39.9 ± 0.3 g L−1 with a productivity of 0.926 ± 0.006 g L−1 h−1. The observed productivity was nearly threefold greater than previously reported for glutamic acid-independent production using the strain TISTR 1010. The molecular weight of γ-PGA was in the approximate range of 60 to 135 kDa.
      PubDate: 2017-07-01
      DOI: 10.1007/s12010-016-2376-1
      Issue No: Vol. 182, No. 3 (2017)
  • Structural Insight into the Gene Expression Profiling of the hcn Operon in
           Pseudomonas aeruginosa
    • Authors: Nilkanta Chowdhury; Angshuman Bagchi
      Pages: 1144 - 1157
      Abstract: Pseudomonas aeruginosa is a common opportunistic human pathogen. It generally attacks immunosuppressed patients like AIDS, cancer, cystic fibrosis, etc. The virulence of P. aeruginosa is mediated by various virulence factors. One of such potential virulence factors is HCN synthesized by HCN synthase enzyme, which is encoded by the hcnABC operon. The expressions of the genes of this operon are regulated by three transcriptional regulators, viz., LasR, ANR, and RhlR. In our previous work, we analyzed the molecular details of the functionalities of LasR. In this work, we focused on ANR. ANR is a regulatory protein which belongs to the FNR family and works in anaerobic condition. ANR binds to the promoter DNA, named ANR box, as a dimer. The dimerization of this ANR protein is regulated by Fe4S4, an iron-sulfur cluster. This dimer of ANR (ANR-Fe4S4/ANR-Fe4S4) recognizes and binds the promoter DNA sequence and regulates the transcription of this hcnABC operon. Till date, the biomolecular details of the interactions of ANR dimer with the promoter DNA are not fully understood. Thus, we built the molecular model of ANR-Fe4S4/ANR-Fe4S4. We docked the complex with the corresponding promoter DNA region. We analyzed the mode of interactions with the promoter DNA under different conditions. Thus, we tried to analyze the functionality of the ANR protein during the expressions of the genes of the hcnABC operon. So far, this is the first report to detail the molecular mechanism of the gene expression in P. aeruginosa.
      PubDate: 2017-07-01
      DOI: 10.1007/s12010-016-2388-x
      Issue No: Vol. 182, No. 3 (2017)
  • Identification of the Catalytic Residue of Rat Acyl-CoA Dehydrogenase 9 by
           Site-Directed Mutagenesis
    • Authors: Jia Zeng; Senwen Deng; Yiping Wang
      Pages: 1198 - 1207
      Abstract: Acyl-CoA dehydrogenase 9 (ACAD 9) is the ninth member of ACADs involved in mitochondrial fatty acid oxidation and possibly complex I assembly. Sequence alignment suggested that Glu389 of rat ACAD 9 was highly conserved and located near the active center and might act as an important base for the dehydrogenation reaction. The role of Glu389 in the catalytic reaction was investigated by site-directed mutagenesis. Both wild-type and mutant ACAD 9 proteins were purified and their catalytic characterization was studied. When Glu389 was replaced by other residues, the enzyme activity could be lost to a large extent. Those results suggested that Glu389 could function as the catalytic base that abstracted the α-proton of the acyl-CoA substrate in a proposed catalytic mechanism.
      PubDate: 2017-07-01
      DOI: 10.1007/s12010-016-2392-1
      Issue No: Vol. 182, No. 3 (2017)
  • Erratum to: Degradation of Lignin in Agricultural Residues by locally
           Isolated Fungus Neurospora discreta
    • Authors: Sirisha Pamidipati; Asma Ahmed
      Pages: 1256 - 1257
      PubDate: 2017-07-01
      DOI: 10.1007/s12010-016-2380-5
      Issue No: Vol. 182, No. 3 (2017)
  • Effects of Liquid Hot Water Pretreatment on Enzymatic Hydrolysis and
           Physicochemical Changes of Corncobs
    • Authors: Saksit Imman; Navadol Laosiripojana; Verawat Champreda
      Abstract: Liquid hot water (LHW) pretreatment is an efficient chemical-free strategy for enhancing enzymatic digestibility of lignocellulosic biomass for conversion to fuels and chemicals in biorefinery. In this study, effects of LHW on removals of hemicelluloses and lignin from corncobs were studied under varying reaction conditions. LHW pretreatment at 160 °C for 10 min promoted the highest levels of hemicellulose solubilization into the liquid phase, resulting into the maximized pentose yield of 58.8% in the liquid and more than 60% removal of lignin from the solid, with 73.1% glucose recovery from enzymatic hydrolysis of the pretreated biomass using 10 FPU/g Celluclast™. This led to the maximal glucose and pentose recoveries of 81.9 and 71.2%, respectively, when combining sugars from the liquid phase from LHW and hydrolysis of the solid. Scanning electron microscopy revealed disruption of the intact biomass structure allowing increasing enzyme’s accessibility to the cellulose microfibers which showed higher crystallinity index compared to the native biomass as shown by x-ray diffraction with a marked increase in surface area as revealed by BET measurement. The work provides an insight into effects of LHW on modification of physicochemical properties of corncobs and an efficient approach for its processing in biorefinery industry.
      PubDate: 2017-07-19
      DOI: 10.1007/s12010-017-2541-1
  • Comparison of Flow Cytometry and ELASA for Screening of Proper Candidate
           Aptamer in Cell-SELEX Pool
    • Authors: Maryam Sadat Nabavinia; Fahimeh Charbgoo; Mona Alibolandi; Fatemeh Mosaffa; Aida Gholoobi; Mohammad Ramezani; Khalil Abnous
      Abstract: Aptamers are single-stranded RNA or DNA, which bind to their target with high affinity and specificity. Method of isolating aptamers against cell surface protein is called cell-SELEX. Common approach for monitoring cell-SELEX developed aptamers is flow cytometry. Since flow cytometry is costly and requires sophisticated equipments, we suggested implementing easy access, high throughput enzyme-link apta-sorbent assay test (ELASA) to confirm the specificity of aptamers selected through cell-SELEX process. In this regard, we compared ELASA and flow cytometry techniques in order to screen potent candidate aptamers against A2780 Rcis cell line, which were selected by cell-SELEX. The obtained results demonstrated that both ELASA and flow cytometry are identical in terms of sensivity and precision for aptamers selection. Then it could be concluded that ELASA method could be used as a versatile, inexpensive procedure for in vito evaluation of isolated aptamers from cell-SELEX based process.
      PubDate: 2017-07-19
      DOI: 10.1007/s12010-017-2548-7
  • In Vitro Anti-inflammatory and Antioxidant Activities of
           3,5,4′-Trihydroxy-6,7-Methylenedioxyflavone- O -Glycosides and Their
           Aglycone from Leaves of Polygonum tinctorium Lour
    • Authors: Shota Tokuyama-Nakai; Hideto Kimura; Tomoe Ishihara; Mitsuo Jisaka; Kazushige Yokota
      Abstract: Polygonum tinctorium Lour (indigo plant) has been regarded as a useful medicinal plant for traditional herbal medicine. The polyphenolic fraction of indigo leaves exhibited anti-inflammatory activities as determined by the suppressed synthesis of nitric oxide (NO) in cultured RAW264 macrophage cells. The acid hydrolysate of the fraction showed much more potent effect than the unhydrolyzed one. In sharp contrast, those fractions of indigo stems had almost no effect. 3,5,4′-Trihydroxy-6,7-methylenedioxyflavone (TMF)-O-glycosides and tryptanthrin were detected exclusively in the extracts of the leaves. The isolated flavonol species were furthermore tested for their anti-inflammatory activities against the synthesis of NO and prostaglandin E2 in the cultured macrophage cells. More potent anti-inflammatory effects were recognized with different aglycones of flavonols than their flavonol O-glycosides. Although the inhibitory effects of TMF were less effective than those of tryptanthrin, the levels of flavonol O-glycosides with TMF were much more abundant than those of tryptanthrin in the leaves. Oral administration of the fraction containing flavonol O-glycosides with TMF into mice revealed the detection of free TMF in the blood circulation, indicating that the aglycone moiety can be cleaved by digestive enzymes and absorbed in the gut. Alternatively, the assay of hydrophilic oxygen radical absorbance capacity revealed that the isolated species of flavonol O-glycosides with TMF and their aglycone had appreciable antioxidant activities. Taken together, our findings suggest that the predominant flavonol O-glycosides with TMF as an aglycone could be promising natural agents for the application to herbal medicine, nutraceuticals, and food additives.
      PubDate: 2017-07-18
      DOI: 10.1007/s12010-017-2555-8
  • Application of Transgalactosylation Activity of β-Galactosidase from
           Kluyveromyces lactis for the Synthesis of Ascorbic Acid Galactoside
    • Authors: Aleksandra Wojciechowska; Robert Klewicki; Michał Sójka; Katarzyna Grzelak-Błaszczyk
      Abstract: In view of a commonly known beneficial role and low stability of ascorbic acid, many efforts are constantly undertaken to produce its improved derivatives. This paper presents results on the synthesis of ascorbic acid galactoside using transgalactosylation properties of β-galactosidase from Kluyveromyces lactis and lactose as a donor of galactosyl moiety. The purpose of this study was to determine the influence of selected factors (concentration and molar ratio of substrates, amount of the enzyme preparation, pH of the solution, presence of different ions) on the course of transgalactosylation reaction. Research has shown that approx. 2.5% dry matter (d.m.; 12.7 g/L) of ascorbic acid galactoside is formed under favourable conditions (50% (w/v) substrates, sodium ascorbate and lactose at the molar ratio of 1.9:1, enzyme dose of 28,600 U/100 g lactose, pH = 7.0). The addition of Mg2+ or K+ ions to the reaction medium caused an increase in the final product content (even up to approx. 3.4% d.m., 17.2 g/L), while Na+ or Mn2+ had an adverse impact on the yield. The gathered data may be valuable for cosmetic or food industry.
      PubDate: 2017-07-13
      DOI: 10.1007/s12010-017-2551-z
  • Steered Molecular Dynamics for Investigating the Interactions Between
           Insulin Receptor Tyrosine Kinase (IRK) and Variants of Protein Tyrosine
           Phosphatase 1B (PTP1B)
    • Authors: Hung Nguyen; Nhat Do; Tuyn Phan; Tri Pham
      Abstract: The aim of this study is to use steered molecular dynamics to investigate the dissociation process between IRK and PTP1Bs for wild type and five mutants (consisting of p.D181E, p.D181A, p.Q262A, p.D181A-Y46F, and p.D181A-Q262A). The gained results are observed not only the unbinding mechanism of IRK-PTP1B complexes came from pulling force profile, number of hydrogen bonds, and interaction energy between IRK and PTP1Bs but also described PTP1B’s point mutations could variably change its binding affinity towards IRK. Additionally, the binding free energy calculated by Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) is also revealed that electrostatic energy and polar solvation energy mainly made up the binding free energy of PTP1B-IRK complexes.
      PubDate: 2017-07-13
      DOI: 10.1007/s12010-017-2549-6
  • V79 Fibroblasts Are Protected Against Reactive Oxygen Species by Flax
    • Authors: Katarzyna Skórkowska-Telichowska; Anna Kulma; Tomasz Gębarowski; Wioleta Wojtasik; Kamil Kostyn; Helena Moreira; Anna Szyjka; Aleksandra Boba; Marta Preisner; Justyna Mierziak; Malgorzata Arendt; Anna Kostyn; Michał Szatkowski; Jan Szopa; Kazimierz Gąsiorowski
      Abstract: Chinese hamster pulmonary fibroblasts (V79 cells) pre-treated with flax fabrics derived from non-modified or genetically engineered flax fibres and treated with H2O2 revealed a markedly lower level of intracellular reactive oxygen species (ROS) than control, non-pre-treated cells. The fabrics were prepared from fibres derived from two kinds of transgenic plants: W92 plants, which overproduce flavonoids, and M type plants, which produce hydroxybutyrate polymer in their vascular bundles and thus in fibres. Incubating the V79 cells with the flax fabrics prior to H2O2 treatment also reduced the amount of DNA damage, as established using the comet assay (also known as alkaline single-cell gel electrophoresis) and pulsed-field electrophoresis of intact cellular DNA. Selected gene expression analysis revealed the activator impact of fabrics on the apoptotic (BCL2 family, caspases) gene expression. This promoting activity was also detected for histone acetyltransferase (HAT; MYST2) gene expression. The flax fabric derived from both GM flax plants exhibited a protective effect against oxidative stress and ROS-mediated genotoxic damage, but the W92 fabric was the strongest. It is thus suggested that these fabrics might be useful as a basis for new biomedical products (e.g. wound dressings) that actively protect cells against inflammation and degeneration.
      PubDate: 2017-07-08
      DOI: 10.1007/s12010-017-2552-y
  • Assessment of Antioxidant and Antimicrobial Properties of Lignin from Corn
           Stover Residue Pretreated with Low-Moisture Anhydrous Ammonia and
           Enzymatic Hydrolysis Process
    • Authors: Mingming Guo; Tony Jin; Nhuan P. Nghiem; Xuetong Fan; Phoebe X. Qi; Chan Ho Jang; Lingxiao Shao; Changqing Wu
      Abstract: Lignin accounts for 15–35% of dry biomass materials. Therefore, developing value-added co-products from lignin residues is increasingly important to improve the economic viability of biofuel production from biomass resources. The main objective of this work was to study the lignin extracts from corn stover residue obtained from a new and improved process for bioethanol production. Extraction conditions that favored high lignin yield were optimized, and antioxidant and antimicrobial activities of the resulting lignin were investigated. Potential estrogenic toxicity of lignin extracts was also evaluated. The corn stover was pretreated by low-moisture anhydrous ammonia (LMAA) and then subjected to enzymatic hydrolysis using cellulase and hemicellulase. The residues were then added with sodium hydroxide and extracted for different temperatures and times for enhancing lignin yield and the bioactivities. The optimal extraction conditions using 4% (w/v) sodium hydroxide were determined to be 50 °C, 120 min, and 1:8 (w:v), the ratio between corn stover solids and extracting liquid. Under the optimal condition, 33.92 g of lignin yield per 100 g of corn stover residue was obtained. Furthermore, the extracts produced using these conditions showed the highest antioxidant activity by the hydrophilic oxygen radical absorbance capacity (ORAC) assay. The extracts also displayed significant antimicrobial activities against Listeria innocua. Minimal estrogenic impacts were observed for all lignin extracts when tested using the MCF-7 cell proliferation assay. Thus, the lignin extracts could be used for antioxidant and antimicrobial applications, and improve the value of the co-products from the biomass-based biorefinery.
      PubDate: 2017-07-07
      DOI: 10.1007/s12010-017-2550-0
  • In Vivo Evaluation of the Toxic Effect of Ethyl Acetate Extracts of Marine
           Antibiotic Resistance Pseudomonas Species Derived from the Red Sea
    • Authors: Mervat Morsy Abbas Ahmed El-Gendy; Hind A. A. Al-Zahrani; Najlaa Y. Abozinadah; Ahmed Mohamed Ahmed El-Bondkly
      Abstract: Eighty-nine cultured Pseudomonas species isolated from the sediment and water samples collected from five industrial Red Sea regions that have been affected by petroleum and industry. Genotypic (exoT, exoS, exoU, exoY, lasA, lasB, rhlA, rhlB, Pf1, PAGI-1, -2, and -3) and phenotypic (DNase, elastase, lipase, protease, siderophore, antibiotic resistance patterns) characteristics were determined. Out of these isolates, nine Pseudomonas isolates were selected as the hyperactive virulence factors producers along with highly resistant pattern against all antibiotics of different classes included in this study. They were subjected to phenotypic and chemotypic characterization as well as molecular identification through 16S rRNA gene amplification and sequencing. The bioactive metabolites of these nine strains were extracted by ethyl acetate followed by evaluating their cytotoxic activity toward liver tissues, kidney tissues, and other biochemical activities in rat. Both EGY6 and EGY8 caused the highest significant reduction in the levels of packed cell volume (PCV), red blood cell count (RBC), and hemoglobin (Hb), which indicate that these Pseudomonas strain metabolites could cause anemia and toxic effects on hematological values in animals that were infected with them. Rats treated with the most toxic extract, EGY8, showed severe histopathological alterations in liver and kidney.
      PubDate: 2017-07-06
      DOI: 10.1007/s12010-017-2553-x
  • A BioDesign Approach to Obtain High Yields of Biosimilars by
           Anti-apoptotic Cell Engineering: a Case Study to Increase the Production
           Yield of Anti-TNF Alpha Producing Recombinant CHO Cells
    • Authors: Sultan Gulce Iz; Muge Anil Inevi; Pelin Saglam Metiner; Duygu Ayyildiz Tamis; Nazli Kisbet
      Abstract: Recent developments in medical biotechnology have facilitated to enhance the production of monoclonal antibodies (mAbs) and recombinant proteins in mammalian cells. Human mAbs for clinical applications have focused on three areas, particularly cancer, immunological disorders, and infectious diseases. Tumor necrosis factor alpha (TNF-α), which has both proinflammatory and immunoregulatory functions, is an important target in biopharmaceutical industry. In this study, a humanized anti-TNF-α mAb producing stable CHO cell line which produces a biosimilar of Humira (adalimumab) was used. Adalimumab is a fully human anti-TNF mAb among the top-selling mAb products in recent years as a biosimilar. Products from mammalian cell bioprocesses are a derivative of cell viability and metabolism, which is mainly disrupted by cell death in bioreactors. Thus, different strategies are used to increase the product yield. Suppression of apoptosis, also called anti-apoptotic cell engineering, is the most remarkable strategy to enhance lifetime of cells for a longer production period. In fact, using anti-apoptotic cell engineering as a BioDesign approach was inspired by nature; nature gives prolonged life span to some cells like stem cells, tumor cells, and memory B and T cells, and researchers have been using this strategy for different purposes. In this study, as a biomimicry approach, anti-apoptotic cell engineering was used to increase the anti-TNF-α mAb production from the humanized anti-TNF-α mAb producing stable CHO cell line by Bcl-xL anti-apoptotic protein. It was shown that transient transfection of CHO cells by the Bcl-xL anti-apoptotic protein expressing plasmid prolonged the cell survival rate and protected cells from apoptosis. The transient expression of Bcl-xL using CHO cells enhanced the anti-TNF-α production. The production of anti-TNF-α in CHO cells was increased up to 215 mg/L with an increase of 160% after cells were transfected with Bcl-xL expressing plasmid with polyethylenimine (PEI) reagent at the ratio of 1:6 (DNA:PEI). In conclusion, the anti-apoptotic efficacy of the Bcl-xL expressing plasmid in humanized anti-TNF-α MAb producing stable CHO cells is compatible with curative effect for high efficiency recombinant protein production. Thus, this model can be used for large-scale production of biosimilars through transient Bcl-xL gene expression as a cost-effective method.
      PubDate: 2017-07-06
      DOI: 10.1007/s12010-017-2540-2
  • MgO Nanoparticle-Catalyzed Synthesis and Broad-Spectrum Antibacterial
           Activity of Imidazolidine- and Tetrahydropyrimidine-2-Thione Derivatives
    • Authors: Hamid Beyzaei; Somaye Kooshki; Reza Aryan; Mohammad Mehdi Zahedi; Alireza Samzadeh-Kermani; Behzad Ghasemi; Mohammadreza Moghaddam-Manesh
      Abstract: The biological properties of imidazolidine- and tetrahydropyrimidine-2-thione derivatives such as antiviral, antitumor, anti-inflammatory, and analgesic activities increase the demand for mild and efficient synthetic routes. In this regard, methods such as reaction of diaminoalkanes with carbon disulfide have been developed. However, this method usually suffers from relatively long reaction times, using excess reagents, vigorous reaction conditions, and emission of pernicious hydrogen sulfide gas. In this project, MgO nanoparticle was used as an efficient, non-toxic, recyclable, and economic catalyst to synthesize cyclic five- or six-membered thioureas 3a–h via reaction of 1:1 molar ratios of 1,2- or 1,3-diaminoalkanes 1a–h and carbon disulfide in ethanol at ambient temperature. More interestingly, no hydrogen sulfide emission was detected during the reaction progress. The in vitro antimicrobial properties of synthesized compounds were investigated against 14 different Gram-positive and Gram-negative pathogenic bacteria according to CLSI (Clinical and Laboratory Standards Institute) broth microdilution and disk diffusion methods. The results were compared to those of penicillin, gentamicin, and ceftriaxone, and reported as inhibition zone diameter (IZD), the minimum inhibitory concentration (MIC), and the minimum bactericidal concentration (MBC) values. The best inhibitory effects were observed with imidazolidine-2-thiones 3c and 3d. They were effective against 14 and 11 pathogens, respectively. The structure-activity relationships of the prepared heterocyclic compounds were also studied.
      PubDate: 2017-07-05
      DOI: 10.1007/s12010-017-2544-y
  • pH-Sensitive Self-Assembled Microspheres Composed of Poly(Ethyleneimine)
           and Cinnamic Acid
    • Authors: Danbi Park; Seung-Jun Lee; Jin-Chul Kim
      Abstract: Microspheres which were sensitive to pH change were developed by utilizing cinnamic acid (CA) as a physical cross-linker for poly(ethyleneimine) (PEI). At pH 7.0, the microspheres were efficiently formed at the PEI/CA ratio of 1:3.4, 1:5.1, and 1:7.1 (w/w), which corresponded to the protonated amino group/deprotonated carboxyl group ratio of 5:5, 4:6, and 3:7. The mean diameter of wet microspheres was 3.2 ± 0.3 to 8.8 ± 0.5 μm and that of dry ones was 1.7 ± 0.2 to 2.7 ± 0.2 μm. The microspheres were disappeared upon the alkalification, possibly because the electrostatic interaction between PEI and CA was slackened down and the hydrophobic interaction among CA molecules was weakened. At pH 5.0 and 7.0, the microsphere released its content in a sustained manner and the release degree in 24 h was less than 40%. Whereas, at pH 8.0 and 9.0, the microsphere exhibited a burst release and the release degree in 24 h was greater than 80%. In the alkali condition, not only the electrostatic interaction between PEI and CA but also the hydrophobic interaction among CA molecules became weaker, leading to the disintegration of the microsphere and resulting in a burst and intensive release.
      PubDate: 2017-07-04
      DOI: 10.1007/s12010-017-2534-0
  • Production of High Commercial Value Xylooligosaccharides from Meranti Wood
           Sawdust Using Immobilised Xylanase
    • Authors: Siti Sabrina Mohd Sukri; A.M. Mimi Sakinah
      Abstract: The present study explores the utilisation of a new raw material from lignocellulose biomass, Meranti wood sawdust (MWS) for high commercial value xylooligosaccharides (XOS) production using immobilised xylanase. The xylanase was immobilised by a combination of entrapment and covalent binding techniques. The hemicellulosic xylan from MWS was extracted using a standard chlorite delignification method. The production of total and derivatives of XOS from the degradation of the hemicellulosic xylan of MWS were compared to the production from the commercial xylan from Beechwood. The utilisation of the extracted xylan from MWS yielded 0.36 mg/mL of total XOS after 60 h of hydrolysis. During the hydrolysis reaction, the immobilised xylanase released a lower degree of polymerisation (DP) of XOS, mainly X2 and X3, which were the major products of xylan degradation by xylanase enzymes. The production of XOS with a lower DP from MWS demonstrated the biotechnological potential of the MWS in the future. The XOS production retained about 70% of its initial XOS production during the second cycle. This is also the first report on the utilisation of MWS wastes in enzymatic hydrolysis using immobilised xylanase for XOS production.
      PubDate: 2017-07-04
      DOI: 10.1007/s12010-017-2542-0
  • Lignin Sulfonation and SO 2 Addition Enhance the Hydrolyzability of
           Deacetylated and Then Steam-Pretreated Poplar with Reduced Inhibitor
    • Authors: Yong Tang; Xiaoli Dou; Jinguang Hu; Jianxin Jiang; Jack N. Saddler
      Abstract: The merit of deacetylation of corn stover prior to pretreatment is decreasing the formation of inhibitors and improving enzyme hydrolysis, proved in dilute acid pretreatment. However, few studies are done on how deacetylation would affect bioconversion process containing steam explosion. In this study, the effect of deacetylation on steam explosion was conducted using poplar as substrate. About 57 to 90% of acetyl group in poplar, depending on alkaline types and concentration, was removed by dilute alkaline deacetylation in 6 h. Deacetylation eliminated over 85% of inhibitor formation during downstream steam explosion. However, deacetylation prior to steam explosion decreased the dissolution of hemicellulose, thus reducing the cellulose accessibility of pretreated poplar, finally resulting in 5–20% decrease in glucose yield and 20–35% decrease in xylose yield. The addition of 5% SO2 during steam explosion significantly improved the hydrolysis of deacetylated and pretreated poplar without significantly increasing the concentration of inhibitors. Incorporating 45 mmol/kg sulfoacid group in lignin fraction of deacetylated and then pretreated poplar dramatically improved the xylose yield to about 100% and increased the glucose yield by 30%.
      PubDate: 2017-07-04
      DOI: 10.1007/s12010-017-2545-x
  • Cloning, Purification, and Characterization of Tripeptidyl Peptidase from
           Streptomyces herbaricolor TY-21
    • Authors: Keisuke Ekino; Shinichi Yonei; Hiroshi Oyama; Takuji Oka; Yoshiyuki Nomura; Takashi Shin
      Abstract: Tripeptidyl peptidase (TPP) is an exopeptidase that sequentially hydrolyzes tripeptides from the N-terminus of oligopeptides or polypeptides. We performed screening for isolating novel TPP-producing microorganisms from soil samples. TPP activity was observed in the culture supernatant of Streptomyces herbaricolor TY-21 by using Ala-Ala-Phe-p-nitroanilide (pNA) as the substrate. TPP from the culture supernatant was purified to approximately 790-fold. It was shown to cleave oxidized insulin B-chain, thereby with releasing tripeptide units, but not the N-terminal-protected peptide, Cbz-Ala-Ala-Phe-pNA. The TPP gene, designated tpp, was isolated from a partial genomic DNA library of S. herbaricolor TY-21. The TPP gene consisted of 1488 bp, and encoded a 133-amino acid pre-pro-peptide and a 362-amino acid mature enzyme containing conserved amino acid residues (Asp-36, His-77, and Ser-282) similar to the catalytic residues in subtilisin. TY-21 TPP belonged to the peptidase S8A family in the MEROPS database. The mature TY-21 TPP showed approximately 49% identity with tripeptidyl peptidase subtilisin-like (TPP S) from Streptomyces lividans strain 66.
      PubDate: 2017-07-03
      DOI: 10.1007/s12010-017-2547-8
  • Heterologous Expression and Characterization of an Acidic GH11 Family
           Xylanase from Hypocrea orientalis
    • Authors: Hailong Li; Hongli Wu; Fengjiao Jiang; Jinlian Wu; Yong Xue; Lihui Gan; Jian Liu; Minnan Long
      Abstract: A gene encoding glycoside hydrolase family 11 xylanase (HoXyn11B) from Hypocrea orientalis EU7–22 was expressed in Pichia pastoris with a high activity (413 IU/ml). HoXyn11B was partly N-glycosylated and appeared two protein bands (19–29 kDa) on SDS-PAGE. The recombinant enzyme exhibited optimal activity at pH 4.5 and 55 °C, and retained more than 90% of the original activity after incubation at 50 °C for 60 min. The determined apparent K m and V max values using beechwood xylan were 10.43 mg/ml and 3246.75 IU/mg, respectively. The modes of action of recombinant HoXyn11B on xylo-oligosaccharides (XOSs) and beechwood xylan were investigated by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), which indicated that the modes of action of HoXyn11B are different from HoXyn11A since it is able to release a significant amount of xylose from various substrates. This study provides an opportunity to better understand the hydrolysis mechanisms of xylan by xylanases from Trichoderma.
      PubDate: 2017-07-03
      DOI: 10.1007/s12010-017-2532-2
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