The last two pathway-specific enzyme activities of hexosamine biosynthesis are present in Blastocladiella emersonii zoospores prior to germination

Forward direction assays have been developed for the last two pathway-specific enzymes of hexosamine biosynthesis using crude extracts from Blastocladiella emersonii zoospores. The specific enzyme activities measured are substantially higher than those reported with enzyme preparations from other organisms. During the development of one of the assays, another enzyme activity was observed which converts one of the intermediates of the pathway, N-acetylglucosamine-6-phosphate, to N-acetylglucosamine. The finding of these three enzyme activities in zoospore extracts completes the demonstration that all the enzyme activities necessary to synthesize some 2% by weight as chitin early during zoospore germination (de novo cell wall formation) pre-exist in the zoospore. This demonstration is consistent with the conclusion that the hexosamine pathway is regulated at the post-translational level during zoospore germination.