Calorimetric studies on hydrolysis of glucosides. V. Heats of hydrolysis of cyclohexa-, cyclohepta-, and cyclooctaamyloses and thermodynamic considerations on the cyclization process.

Abstract

1. Calorimetric studies have been made on the hydrolytic reactions of cyclohex-, cyclohepta-, and cyclooctaamyloses catalyzed by mixed enzyme system of glucoamylase**** and Taka-amylase A***** at 25°C. 2. The average heats of hydrolysis of α-1, 4 glucosidic linkage, ΔH1, 4, involved in cyclohexa-, cyclohepta-, and cyclootaamyloses have been obtained to be –2,130 cal/mole, –1,660 cal/mole, and –1,580 cal/mole, respectively. 3. On the basis of enthalpy values known for α-1, 4 glucosidic linkage of noncyclic nature, the energetic instability introduced by the cyclization has been evaluated. 4. The cyclization process of linear glucose chain to form cyclohexa-, cyclohepta-, and cyclooctaamyloses has been discussed in view of thermodynamics.