Isocitritase, Glycine-Alanine Transaminase, and Development in Blastocladiella Emersonii

Abstract

The enzyme, isocitritase, which had been postulated to play an important role in the development of B. emersonii, has been purified about 50 fold from extracts of this organism and some of its properties studied. Its pH optimum is 7.4, its Michaelis constant 4.8 x 10-4 [image] and it is specific for the D-siomer of isocitric acid. A 2d enzyme, glycine-alanine transaminase, which has not been previously described, was purified ca 80 fold and its properties similarly examined. New methods were developed which permitted, for the first time among aquatic fungi, precise, enzymological studies at all stages of the synchronized growth of single-generation populations of Blastocladiella, from zoospores to the mature, ordinary colorless plants. The synthesis of isocitritase and glycine-alanine transaminase was followed during the development of both colorless and resistant-sporangial plants. By studying both the specific activities of these two enzymes and their total activities per plant, an attempt was made to integrate the results into an interpretation of the function of these enzymes in morphogenesis and "lumisynthesis" (light-stimulated growth) in B. emersonii.