کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6490289 | 1416967 | 2018 | 35 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Increasing thermal stability of glutamate decarboxylase from Escherichia. coli by site-directed saturation mutagenesis and its application in GABA production
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
بیو مهندسی (مهندسی زیستی)
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چکیده انگلیسی
Gamma-amino butyric acid (GABA) is an important bio-product used in pharmaceuticals, functional foods, and a precursor of the biodegradable plastic polyamide 4 (Nylon 4). Glutamate decarboxylase B (GadB) from Escherichia. coli is a highly active biocatalyst that can convert l-glutamate to GABA. However, its practical application is limited by the poor thermostability and only active under acidic conditions of GadB. In this study, we performed site-directed saturation mutagenesis of the N-terminal residues of GadB from Escherichia coli to improve its thermostability. A triple mutant (M6, Gln5Ile/Val6Asp/Thr7Gln) showed higher thermostability, with a 5.6 times (560%) increase in half-life value at 45â¯Â°C, 8.7â¯Â°C rise in melting temperature (Tm) and a 14.3â¯Â°C rise in the temperature at which 50% of the initial activity remained after 15â¯min incubation (T1550), compared to wild-type enzyme. Protein 3D structure analysis showed that the induced new hydrogen bonds in the same polypeptide chain or between polypeptide chains in E. coli GadB homo-hexamer may be responsible for the improved thermostability. Increased thermostability contributed to increased GABA conversion ability. After 12â¯h conversion of 3â¯mol/L l-glutamate, GABA produced and mole conversion rate catalyzed by M6 whole cells was 297â¯g/L and 95%, respectively, while those by wild-type GAD was 273.5â¯g/L and 86.2%, respectively.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Biotechnology - Volume 278, 20 July 2018, Pages 1-9
Journal: Journal of Biotechnology - Volume 278, 20 July 2018, Pages 1-9
نویسندگان
Li-Qiang Fan, Ming-Wei Li, Yong-jun Qiu, Qi-ming Chen, Si-Jing Jiang, Yu-Jie Shang, Li-Ming Zhao,