Abstract
The action of Chalara paradoxa glucoamylase (raw-starch-digesting enzyme) was studied with linear and cyclic maltodextrins. Subsite affinities (Ai) of the amylase were evaluated by the subsite theory. The active site was considered to be made up of seven subsites: A1 = 0.05 kcal/mol, A2= 4.99 kcal/mol, A3 = 1.30 kcal/mol, A4 = 0.77 kcal/mol, A5= 0.33 kcal/mol, A6 = 0.21 kcal/mol and A7 = 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 3.9 HIM, respectively. The Michaelis constant (Km) of 6-O-α-maltosyl-α-cyclodextrin digestion was 0.79 mM for the amylase.
