HETEROGENEITY OF PHENOL OXIDASES IN CRYPTOCOCCUS-NEOFORMANS

Phenol oxidase enzymes, linked to virulence in Cryptococcus neoformans, were prepared from broken cells. More enzyme activity was found in the ultracentrifugation supernatant; less was found in the membrane fraction. Phenol oxidases were located in acrylamide gel electropherograms by activity staining with L-dihydroxyphenylalanine (DOPA). Mobility differences between soluble and solubilized membrane-bound phenol oxidases were not found. Comparison of enzymes produced at 25 and 37-degrees-C revealed that the enzyme had lower activity and lower mobility at 37-degrees-C. The mobility of 25-degrees-C phenol oxidases from strains of C. neoformans var. gattii was lower than that of those from C. neoformans var. neoformans. Half of the phenol oxidase produced at 25-degrees-C was bound by concanavalin A, while that produced at 37-degrees-C was not bound. However, glucose starvation of cultures at 25-degrees-C overnight resulted in increased amounts of enzyme which did not bind to concanavalin A. A given strain of C. neoformans produces different species of phenol oxidase under different culture conditions.