Purification and characterization of an alkaline serine endopeptidase from a feather-degradingXanthomonas maltophiliastrain

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.

Purification and characterization of keratinase from a new Bacillus subtilis strain

“…But for the keratinase from B. subtilis KD-N2 strain, all metal ions have negative effects on its activity. Serine-proteinase inhibitor PMSF partially inhibited the keratinase activity, which is identical to most of the keratinases studied except for a few from Paecilomyces marquandii, Doratomyces microsporus and Xanthomonas maltophilia, which are fully inhibited (de Toni et al, 2002;Gradišar et al, 2005). EDTA has negative effects on activities of mostly reported keratinases, but we observed in this study that the keratinase from B. subtilis KD-N2 strain was stimulated by 5 mmol/L EDTA, similar to the keratinase from Fervidobacterium islandicum AW-1 (Nam et al, 2002).…”

Purification and Molecular Weight Determination of Keratinase Isolated From Streptomyces Malaysiensis

“…Although keratinases from dematophytic fungi have long been well known due to their notorious pathogenic nature [6] these enzymes have only recently gained biotechnological impetus. Their growing importance is mainly contributed to the isolation of keratinases from non-pathogenic microorganisms and their ability to degrade the tough insoluble keratin of feather and convert it into economically useful feather meal [7][8][9], nitrogenous fertilizers, biodegradable films, glues and foils [10,11].…”

Hydrolysis of insoluble fish protein residue from whitemouth croaker (Micropogonias furnieri) by fungi

“…This tendency to alkalinize the medium results from the production of ammonia due to deamination of peptides and amino acids originating from keratin degradation. The resulting increase of pH is typical of microorganisms growing on protein substrates (De Toni et al 2002;Riffel et al 2003;Gradisar et al 2005). The pH increase during the fermentative process is an important indiciation of the keratinolytic potential of microorganisms (Kim et al 2001).…”