Abstract
In order to obtain more information of glycogen degradating metabolism in bonito skeletal muscle (red muscle), the glycogen debranching system (EC 2.4.1.25+EC 3.2.1.33) was purified and its properties were investigated.
SDS electrophoresis showed that the purified enzyme appears to be made up of a single poly-peptide of molecular weight=165000. With a substrate, phosphorylase limit dextrin as the best substrate and α-1, 6-glucosyl cyclodextrin was hydrolyzed by the enzyme, but glycogen and other related polysaccharides were not hydrolyzed, The enzyme have two different activities containing both α-1, 6-glucosidase and glycosyltransferase. Sulfhydryl group reactivity of the enzyme and the inactivation by pH and temperature were reduced by the exogenous addition of glycogen or soluble starch. The debranching system appears to play no rate-limiting role in the process of glycogen degradation by phosphorylase.
