The α-amylase of the beetle Callosobruchus chinensis properties
- 1 January 1971
- journal article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 121 (2), 321-325
- https://doi.org/10.1042/bj1210321
Abstract
C. chinensis larval amylase is activated by Ca2+ and inhibited by Cl− and EDTA (Ki 6.7×10−3m). GSH and 2-mercaptoethanol activate, presumably at different sites, as 2-mercaptoethanol interferes with Ca2+ activation, whereas GSH enhances it. The inhibition by iodoacetic acid and N-ethylmaleimide (Ki 1.55×10−2m) suggest that free thiol groups are essential for activity. The pH optimum of 5.2–5.4 is moved to 5.6–5.8 by Ca2+ and 2-mercaptoethanol. The activation energy is 7270 cal/mol, and is not affected by Ca2+ and 2-mercaptoethanol. Km for soluble starch is 2.3mg/ml.Keywords
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