Enzymes of glycogen metabolism in developing embryos of a teleost.

An acceleration of glycogenolysis after fertilization in loach (Misgurnus fossilis L.) eggs is not related to an increase of active phosphorylase (EC 2.4.1.1). The activity of "debranching" enzymes (amylo-1,6-glucosidase; dextrin-6-glucohydrolase, EC 3.2.1.33) considerably increases during early embryogenesis. These facts suggest that the enhancement of debranching enzyme activity is the controlling factor of glycogenolysis at early stages of embryonic development.Only 15-20% of the amylo-1,6-glucosidase and phosphorylase is found to be firmly associated with a particular glycogen fraction both in oocytes and embryos. The onset of glycogenolysis after fertilization is not accompanied by redistribution of the above-mentioned enzymes between different fractions of glycogen.