Substrate Stabilization of Soluble and Immobilized Glucoamylase Against Heating
Glucoamylase (1, 4-α-D-glucan glucohydrolase, E.C. 22.214.171.124) catalyzes the hydrolytic cleavage of glucose units from the non-reducing end of starch and the products of partial starch hydrolysis. In the last decade this enzyme has received considerable attention owing to its great industrial usefulness in the soluble form and to its potential use in the immobilized form for production of glucose from starch maltodextrines. We have been especially interested in the production of immobilized glucoamylase that possesses high thermostability at 60 to 65°C. We believe that immobilized glucoamylase that has a half-life of about 3 to 4 weeks at 65°C could be considered a technologically feasible preparation with respect to thermostability. However, in spite of a great number of papers published on the immobilization of this enzyme, the half-life of most stable insoluble preparations at 65°C does not exceed 5 to 7 days (1,2). The question arises as to whether or not this value is characteristic of a certain limit of thermostability of glucoamylase. The answer to this question is important; because from both the theoretical and practical viewpoints it is very important to study the principles of thermostability of glucoamylase and to reveal possibilities for increasing the resistance of this enzyme to thermal action.
KeywordsImmobilize Enzyme Porous Glass Apparent Rate Constant Soluble Enzyme Succinic Anhydride
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