Über das V orkommen differenter Ureohydrolasen in Pilzfruchtkörpern von Panus tigrinus (Bull. ex Fr.) Sing

Abstract

The fungus Panus tigrinus (Bull. ex FR.) Sing. was cultivated under sterile and controlled conditions either on a complex malt-agar-medium with poor arginine content or on a synthetic saccharose-arginine-medium. In the former case stipulae developed after 18 days and fructification was completed after 22-24 days. Fruit-bodies contain the following guanido compounds: L-arginine, agmatine, arcain, and γ-guanidobutyric acid. Different ureohydrolases have been demonstrated which hydrolytically cleave these guanidines to urea and the respective amino compounds. One of them, γ-guanidobutyric acid-ureohydrolase, has been purified about 105-fold. The purified enzyme was free from arginase or any other ureohydrolase activity. The γ-guanidobutyric acid hydrolysis depends on Mn2+ions and is optimal at pH 9,6-9,8. The KM-value with 0,025 M substrate and 3 × 10 −4 M MnCl 2 was estimated to 4,4 × 10 −3 M. The activities of the urehydrolases which are involved in the hydrolytic cleavage of Larginine, arcain, β-guanidopropionic acid, and γ-guanidobutyric acid, respectively, are dependent on the developmental stage of the fungal material. The activity of γ-guanidobutyric acid-ureohydrolase is significantly higher in 5 days old mycelium and in fruit-bodies than in 23 days old mycelium or in stipulae and is much higher in all of the investigated developmental stages than any other urehydrolase activity present. Arginase activity has been found low in each case and is evidently not inducable by growth on the arginine-rich medium employed. From the estimation of γ-guanidobutyric acid-ureohydrolase activities under different culture conditions follows that enzyme activity is much lowerin mycelium and fruit-bodies which have been cultivated on the synthetic saccharose-arginine medium as compared with the material from complex malt-agar medium. This finding needs futher clarification.