title: Purification and characterization of an alkaline serine endopeptidase from a feather-degrading Xanthomonas maltophilia strain.
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.
authors.affiliation: Departamento de Bioquímica and Centro de Biotecnologia, UFRGS, Porto Alegre, RS, Brazil.
authors.forename: C H
authors.initials: CH
authors.lastname: De Toni
authors.forename: M F
authors.initials: MF
authors.lastname: Richter
authors.forename: J R
authors.initials: JR
authors.lastname: Chagas
authors.forename: J A P
authors.initials: JA
authors.lastname: Henriques
authors.forename: C
authors.initials: C
authors.lastname: Termignoni
mesh_terms: D000818:Animals; D002847:Chromatography, Agarose; D005241:Feathers / Q000378:metabolism*; D007633:Keratins / Q000378:metabolism*; D010447:Peptide Hydrolases; D011480:Protease Inhibitors; D012697:Serine Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism*; D020615:Stenotrophomonas maltophilia / Q000201:enzymology* / Q000378:metabolism
chemical_list: D011480:Protease Inhibitors; D007633:Keratins; D010447:Peptide Hydrolases; C035855:keratinase; D012697:Serine Endopeptidases