Subsite Structure of Rhizopus niveus Glucoamylase, Estimated with the Binding Parameters for Maltooligosaccharides

Based on K d and K i for maltosaccarides G n (n = 1 ± 7) and on a specified mode of their binding, the intrinsic affinities A 1 , A 2 , –, A i at subsites i (i = 1 ± 5), were tried to estimate for glucoamylase from Rhizopus niveus . Previously, we have evaluated the apparent values A i using K m and k 0 on the enzyme‐catalyzed hydrolysis for G n , where A 1 is nearly 0 kcal/mol. Thus A 1 , which was found here 3.3 kcal/mol, may be cancelled out with the heat, which is consumed for the hydrolytic cleavage of a substrate glucosyl bond.