[Isolation and comparative properties of serine proteinases of the microscopic fungi Trichoderma lignorum and...

Using affinity chromatography on bacitracin-Sepharose combined with ion-exchange chromatography on aminosilochrome and isoelectrofocusing, individual serine proteases have been isolated for the first time from surface cultures of T. lignorum and T. koningii. The proteinases have pI values at 6.8 and 6.7 and pH optima of 10.5. Both proteinases are stable within the pH range of 4-11 and have molecular weight of 21 000. The amino acid composition of T. lignorum enzyme is Lys3His4Arg9Asx23Thr17Ser23Glx10Pro8Gly27Ala25Cys3Val13Met2Ile11Leu11Tyr7Phe6Tr p3, that of the T. koningii enzyme is Lys3His4 Arg9Asx23Thr16Ser26Glx10Pro9Gly29Ala26Cys3Val14Met2Ile9Leu11Tyr6Phe5Trp3. The enzymes are completely inhibited by phenylmethylsulfonylfluoride, diphenylcarbamoylchloride and trypsin inhibitors from beans, Actinomyces janthinus and potato tubers. The enzymatic and molecular properties of the enzymes are similar to those of subtilisins and previously described fungal serine proteinases, especially to those of proteinase K of the fungus Tritirachium album Limber.