Subsite Structure of Chalara paradoxa Glucoamylase and Interaction of the Glucoamylase with Cyclodextrins(Biological Chemistry)

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The action of Chalara paradoxa glucoamylase (raw-starch-digesting enzyme) was studied with linear and cyclic maltodextrins. Subsite affinities (A_i) of the amylase were evaluated by the subsite theory. The active site was considered to be made up of seven subsites: A_1 = 0.05 kcal/mol, A_2 = 4.99 kcal/mol, A_3 = 1.30 kcal/mol, A_4 = 0.77 kcal/mol, A_5 = 0.33 kcal/mol, A_6 = 0.21 kcal/mol and A_7 = 0.21 kcal/mol. Inhibitions by alpha-, beta-, and gamma-cyclodextrins were competitive for starch digestion by C. paradoxa glucoamylase. The inhibitor constants (Ki) of α-, β-, and γ-cyclodextrin for the amylase were 8.9, 1.4, and 3.9mM, respectively. The Michaelis constant (Km) of 6-O-α-maltosyl-α-cyclodextrin digestion was 0.79 mM for the amylase.
社団法人日本農芸化学会の論文
1989-06-23