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KMID : 1007520200290030409
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Food Science and Biotechnology
2020 Volume.29 No. 3 p.409 ~ p.418
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Functional study of C-terminal domain of the thermoacidophilic raw starch-hydrolyzing α-amylase Gt-amy
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Zeng Jing
Guo Jianjun
Tu Yikun
Yuan Lin
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Abstract
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Since the thermoacidophilic raw-starch hydrolyzing α-amylase Gt-amy can effectively hydrolyze corn starch under starch liquefaction conditions, it has potential for many industrial applications. To identify the raw starch-binding domain of Gt-amy, a C-terminal domain (CTD)-truncated mutant (Gt-amy-T) was constructed, and its enzymatic properties were compared with Gt-amy. In comparison to CTD of Gt-amy, which could effectively bind corn starch, the Gt-amy-T could not bind to and hydrolyze corn starch under similar conditions. In addition, Gt-amy-T showed significantly lower thermal activity and thermal stability. Using soluble starch as the substrate, the kcat of Gt-amy-T at 80 °C was approximately 77.9% of that of Gt-amy. The half-life of Gt-amy at 80 °C was 3 h, while that of Gt-amy-T was 2 h. These results reveal that the CTD plays a vital role in raw starch binding and degradation by Gt-amy and helps Gt-amy maintain thermal activity and stability.
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KEYWORD
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Raw starch-degrading α-amylase, Raw starch-binding domain, Raw starch hydrolysis, Thermal activity, Thermal stability
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