A BACTERIAL GLUCOAMYLASE DEGRADING CYCLODEXTRINS - PARTIAL-PURIFICATION AND PROPERTIES OF THE ENZYME FROM A FLAVOBACTERIUM SPECIES

A Flavobacterium sp. was isolated which produces a cyclodextrin-degrading glucoamylase. The inducible, cell-bound enzyme was purified about 10-fold to 75% purity in 57% yield. The action of the enzyme was studied with the main cyclodextrins (cyclohexaamylose, cycloheptaamylose and cyclooctaamylose) and with the typical glucoamylase substrates. The final degradation product with all the substrates was glucose. Small amounts of maltose, which could be detected in the course of cyclodextrin degradation, were hydrolyzed at a lower rate. The V for cyclohexaamylase was .apprx. 14-15 .mu.mol glucose min-1 (mg pure protein)-1, the Km for cyclohexaamylose was 0.142 mM. The enzyme apparently preferred shorter .alpha.-D-glucopyranosyl chains. Besides maltose, amylopectin and glycogen were very poor substrates. Some properties of the enzyme were described.