PROPERTIES OF GLYCOGENOLYTIC ENZYMES FROM FISH MUSCLE

The properties of glycogenolytic enzyme and cr-glucosidase were examin ed by using the crude extracts from the ordinary muscle of five specie s of fish. Highest activities of both enzymes were detected in the ext ract from black sea bream. Optimum pH values of glycogenolytic enzyme from five species of fish ranged from 6.8 to 7.6, whereas those of alp ha-glucosidase showed species-specificity, that is, pH 4.2-4.4 for Pac ific mackerel, ayu and Japanese eel, pH 5.5 for black sea bream, and p H 6.2 for frog flounder. Maximal activities of black sea bream enzymes were observed at 35 degrees C for glycogenolytic enzyme and 40 degree s C for alpha-glucosidase. Glycogenolytic activity fell by 50% during incubation at 20 degrees C for 10 min, whereas alpha-glucosidase activ ity retained 90% of its activity when incubated at 40 degrees C for 10 min. Km values for glycogen and p-nitrophenyl alpha-D-glucoside were 1.8% (pH 6.9) and 7.0 x 10(-4) M (pH 6.0), respectively. The Elution p rofile of glycogenolytic enzyme on Sephacryl S-2O0 revealed a single p eak and its molecular weight was estimated to be 70,000. On the other hand, two active peaks of alpha-glucosidase were observed on the gel f iltration, and their molecular weights were estimated to be 100,000 an d 40,000, respectively. Glycogenolytic activity from the black sea bre am muscle was not activated by NaCl, while the enzyme was activated by 50% by 0.1 mM CaCl2.