Improving the thermostability of raw-starch-digesting amylase from a Cytophaga sp. by site-directed mutagenesis.
A heat-stable raw-starch-digesting amylase (RSDA) was generated through PCR-based site-directed mutagenesis. At 65 degrees C, the half-life of this mutant RSDA, which, compared with the wild-type RSDA, lacks amino acids R178 and G179, was increased 20-fold. While the wild type was inactivated completely at pH 3.0, the mutant RSDA still retained 41% of its enzymatic activity. The enhancement of RSDA thermostability was demonstrated to be via a Ca(2+)-independent mechanism.
Shiau
Rong-Jen
RJ
Department of Food Science, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Hung
Hui-Chen
HC
Jeang
Chii-Ling
CL
D000681:Amylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003589:Cytophaga / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability; D017353:Gene Deletion; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D016297:Mutagenesis, Site-Directed; D013213:Starch / Q000378:metabolism*
D013213:Starch; D000681:Amylases