Similarity of Acid Proteinases Secreted by Candida albicans NIH A-207 and NIH B-792 Strains Cultured in BSA-Supplemented Medium

Abstract

Candida albicans NIH A-207 (serotype A) and NIH B-792 (serotype B) strains secreted one acid proteinases (AP) each in a yeast carbon-based medium supplemented with bovine serum albumin (BSA) as the sole nitrogen source. Isolation of AP from the culture filtrates was achieved by dialysis, followed by DEAE-Sepharose and Biogel P-100 column chromatographies. It was found that both enzymes from the two strains had very similar properties when examined. The molecular weights and isoelectric points were found to be 43 kDa and pH 4.0, respectively. The amino acid components and first 12 N-terminal amino acid sequences were virtually identical in both enzymes. The optimum pH of the enzymes was 3.5-4.0. The enzymes were heat-labile, and decreases in their activities were found above 37 degrees C. The AP activities were completely inhibited by the addition of pepstatin. No other inhibitor among those tested had any effect. The enzymes degraded all proteins examined, especially host defense factors such as immunoglobulin G and the granulocyte colony stimulating factor. The enzymes also caused similar degrees of enhancement of vascular permeability when they were injected into the dorsal skin of guinea pigs.