Cell Wall Synthesis In the Dimorphic Fungus Mucor rouxii: The Formation Of Uridine Diphosphohexoses

Abstract

In this paper the properties of the enzymes UDP glucose dehydrogenase and UDP galactose epimerase were characterized. It was shown that UDP glucose dehydrogenase has a considerable lag period, and is activated by the substrate UDP glucose. This activation may be brought about by a disaggregation. Both enzymes were shown to be labile. For accurate kinetic measurements the dehydrogenase must be separated from the epimerase. The UDP galactose epimerase showed no requirements for exogenous NAD+ and demonstrated slight positive cooperativity for UDP galactose. Experiments were carried out in order to determine the specific activity of UDP glucose dehydrogenase during a 24-hr growth period, but a large variability in the results did not permit one to conclude that the specific activity in the yeast and mycelial forms is significantly different. It is thought that the yeast form may indeed have a higher level of the UDP glucose dehydrogenase than the mycelial form. This problem is discussed.