IDENTIFICATION OF A FUNGAL PROTEIN OF SYNCEPHALASTRUM-RACEMOSUM AS ASPARTIC PROTEINASE

During purification of fungal deoxyribonuclease (DNase) from Syncephal astrum racemosum, a protein which was functionally unknown and persist ently existed in the DNase-containing fractions through chromatography over DEAE cellulose, hydroxylapatite, and phenyl-Sepharose was identi fied. The protein was finally separated from DNase after affinity chro matography on a cibacron blue-Sepharose column and purified to apparen t homogeneity after gel chromatography on a Superdex 200 HR column. Te n tryptic peptides of this protein were isolated and sequenced. Search ing in the sequence data bank with the aid of the computer pro gram PC /Gene, we found that this protein was highly homologous to aspartic pr oteinases, such as pepsin and rhizopuspepsin. Because of its fungal or igin and because the protein indeed showed catalytic cleavage on pepti de bonds of bovine serum albumin, RNase, and carbonic anhydrase, we te rmed this protein syncephapepsin. The molecular weight of syncephapeps in is 38,000 daltons, based on gel filtration and sodium dodecyl sulfa te-polyacrylamide electrophoresis. (C) 1996 Academic Press, Inc.