Purification and characterization of an alkaline serine endopeptidase from a feather-degrading Xanthomonas maltophilia strain |
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Authors: | De Toni C H Richter M F Chagas J R Henriques J A P Termignoni C |
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Institution: | Departamento de Bioquímica and Centro de Biotecnologia, UFRGS, Porto Alegre, RS, Brazil. |
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Abstract: | A keratinolytic Xanthomonas maltophilia strain (POA-1), cultured on feather meal broth, using keratin as its sole source of carbon and nitrogen, secretes several extracellular peptidases. The major serine peptidase was purified to homogeneity by a five-step procedure. Its purity was evaluated by capillary zone electrophoresis. This enzyme has a molecular mass of 36 kDa, an optimum pH of 9.0, and an optimum temperature of 60 degrees C. The inhibitory profile using protease inhibitors shows that this enzyme is a serine endopeptidase. Besides keratin, the enzyme is active upon the substrates azokeratin, azocasein, and the following fluorogenic peptide substrates: Abz-Leu-Gly-Met-Ile-Ser-Leu-Met-Lys-Arg-Pro-Gln-EDDnp, Abz-Lys-Leu-Cys(SBzl)-Gly-Pro-Lys-Gln-EDDnp, and Abz-Lys-Pro-Cys(SBzl)-Phe-Ser-Lys-Gln-EDDnp. |
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