Studies on Aspergillus fumigatus; hydrolysis of polyamino acids by mycelial filtrate and chromatographic fractionation of the filtrate.

Mycelial filtrates from Aspergillus fumigatus (AF), shown to possess haemolytic, toxic, casein precipitating, and protein hydrolyzing activity, hydrolyzed poly-L-lysine and poly-L-glutamine in the pH range 4.6—5.3. Incipient activity against poly-L-lysin was observed at pH 9. Owing to spontaneous hydrolysis of the polyamino acid at pH > 10, no activity optimum could be traced. Gel filtration of mycelial filtrate on Sephadex G-75 or G-100 columns offered no definite information whether the protein hydrolyzing activity, using haemoglobin as substrate, at the optimum pH values, 2.9, 4.6 and 10, shows the activity of a single enzyme with more than 1 pH optimum or of more than 1 enzyme active at different pH values. Certain results of the investigations seem to indicate that the protein hydrolyzing activity at pH 2.9 was not caused by enzymes identical with the enzyme (s) causing the protein hydrolyzing activity at pH 4.6 or pH 10. Casein precipitating and protein hydrolyzing activity occurred, following gel filtration on a Sephadex G-100 column, in identical fractions whereas neither haemolysin nor toxin could be found in samples of 0.5 ml fraction solution from any of the fractions after filtration on Sephadex G-75 or G-100 columns. By using antiserum to a crude filtrate from a homologous AF strain it could be shown, applying immuno-electrophoresis, that dialyzed mycelial filtrate contained 8 precipitating antigens whereas proteinase purified by gel filtration and displaying protein hydrolyzing activity at pH 2.9, pH 4.6 and pH 10 contained 4 such antigens.