EXTRACELLULAR FIBRINOGENOLYTIC ENZYME OF ASPERGILLUS-FUMIGATUS - SUBSTRATE-DEPENDENT VARIATIONS IN THE PROTEINASE SYNTHESIS AND CHARACTERIZATION OF THE ENZYME

To get a better understanding of the role of the previously reported f ibrinogenolytic enzyme of Aspergillus fumigatus, we investigated the i n vitro conditions of enzyme synthesis and attempted to characterize i t. Modification of the nitrogen source did not influence the extracell ular serine-proteinase profile, but resulted in important quantitative differences in the yields in batch cultures. The enzyme synthesis app eared to be an inducible phenomenon in A. fumigatus since it was initi ated exclusively in the presence of proteins or protein hydrolysate. F ree amino acids or inorganic nitrogen compounds could not promote sign ificant enzyme production. Moreover, peptone at a concentration of 0.1 % appeared to be the best inducer of enzyme synthesis. Conversely, mod ification of the carbon source did not affect fungal growth or enzyme synthesis. However, the production of chymotrypsin was highly sensitiv e to the carbohydrate level in the culture medium and, with peptone as nitrogen source, highest yields were obtained in the presence of 0.3 or 0.5% glucose. Culture filtrates of A. fumigatus CBS 113.26 grown wi th peptone or nitrate as nitrogen source were analyzed by sodium dodec yl sulfate-polyacrylamide gel electrophoresis. Comparison of the prote in patterns suggested for the proteinase a molecular mass of 33 kDa wh ich was confirmed by chromatographic purification of the enzyme throug h (Na-CBZ)-D-phenylalanine agarose.