Two Additional Phosphorylases in Developing Maize Seeds

Abstract

Two additional phosphorylases (III and IV) have been detected in developing seeds of maize. Phosphorylase IV is found only in the embryo (with scutellum). It is also present in the embryo of the germinating seed where its activity is 90-fold greater than the activity in the developing embryo 22 days after pollination. Phosphorylase IV is eluted from a DEAE-cellulose column in the same fraction as phosphorylase I of the endosperm, and the 2 enzymes are similar in many respects. Phosphorylase IV is distinguished from phosphorylase I by electrophoretic mobility, by pH optimum, and because its properties are not affected by the shrunken-4 mutation.