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
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی بیو مهندسی (مهندسی زیستی)
پیش نمایش صفحه اول مقاله
Increasing thermal stability of glutamate decarboxylase from Escherichia. coli by site-directed saturation mutagenesis and its application in GABA production
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 45 °C, 8.7 °C rise in melting temperature (Tm) and a 14.3 °C rise in the temperature at which 50% of the initial activity remained after 15 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 12 h conversion of 3 mol/L l-glutamate, GABA produced and mole conversion rate catalyzed by M6 whole cells was 297 g/L and 95%, respectively, while those by wild-type GAD was 273.5 g/L and 86.2%, respectively.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Biotechnology - Volume 278, 20 July 2018, Pages 1-9
نویسندگان
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