CHARACTERIZATION OF A PHENOL OXIDASE FROM CRYPTOCOCCUS-NEOFORMANS VARNEOFORMANS

In Cryptococcus neoformans, enzymic oxidation of various catechols lea ds to melanin, a proposed virulence factor. A phenol oxidase enzyme of Cryptococcus neoformans var. neoformans produced at 25 C has been pur ified from an ultracentrifugal supernatant of an extract of broken cel ls. Hydrophobic interaction chromatography followed by anion-exchange column chromatography allowed purification of the phenol oxidase. The molecular weight of the enzyme estimated by gel filtration was about 8 0,000 and a dimeric species (Mw = 160,000) was suggested. The isoelect ric point of the protein was approximately 4.1. An NH2-terminal 31 ami no acid sequence was determined using phenol oxidase electroblotted on to a PVDF membrane after nondenaturing gel electrophoresis. Upon searc hing the Peptide Institute (Osaka) data base, no proteins with high de grees of homology were found.