Nitrile hydratase (NHase, EC 4.2.1.84) is a metalloenzyme that catalyzes the hydration of nitriles to amides and is mainly used in the industry to produce nicotinamide and acrylamide. In the application process, the common defect of nitrile hydratase is its poor thermal stability. As the process of catalyzing nitrile is an exothermic reaction, during industrial applications, the catalytic efficiency, recovery rate and recycling rate of nitrile hydratase are hindered in large extent. Therefore, discovering new NHase with high thermostability is of great significance for industrial applications and scientific research. In this study, a novel nitrile hydratase was found by BLAST in the Genebank of NCBI from the starting point of heat resistance. The strain was Caldalkalibacillus thermarum TA2.A1,of which the optimum growth temperature was 65-70 ℃. After codon optimization, the NHase gene was heterologously expressed in E. coli BL21 (DE3). The protein was purified by adding strep tag at the C-terminus of the β subunit. The half-life of this novel NHase at 65 ℃ was 3 h and the specific activity towards 3-cyanopyridine was 395 U/mg at 30 ℃. The reaction rate of the whole cell catalysis process at 30 ℃ was nearly twice as fast as the reported data, and the final yield of nicotinamide was increased by 25%, which was more favorable for industrial applications.
ZHANG Sailan
,
LI Ting
,
CHENG Zhongyi
,
ZHOU Li
,
ZHOU Zhemin
,
LIU Zhongmei
,
CUI Wenjing
. Heterologous expression of a novel thermostable nitrile hydratase and its catalytic process[J]. Food and Fermentation Industries, 2020
, 46(14)
: 108
-113
.
DOI: 10.13995/j.cnki.11-1802/ts.023215
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