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

2002 ◽  
Vol 48 (4) ◽  
pp. 342-348 ◽  
Author(s):  
C H De Toni ◽  
M F Richter ◽  
J R Chagas ◽  
J AP Henriques ◽  
C Termignoni
Keyword(s):  
Sole Source ◽  
Peptide Substrates ◽  
Xanthomonas Maltophilia ◽  
Carbon And Nitrogen ◽  
Step Procedure ◽  
Zone Electrophoresis ◽  
Capillary Zone ◽  
Extracellular Peptidases ◽  
Fluorogenic Peptide

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°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.Key words: serine endopeptidase, Xanthomonas maltophilia, keratinase, alkaline endopeptidase.

Characterization of Dissolved Kraft Lignin by Capillary Zone Electrophoresis

1993 ◽  
Vol 13 (4) ◽  
pp. 529-544 ◽  
Author(s):  
Elisabeth Sjöholm ◽  
Nils-Olof Nilvebrant ◽  
Anders Colmsjö
Keyword(s):  
Capillary Zone Electrophoresis ◽  
Kraft Lignin ◽  
Zone Electrophoresis ◽  
Capillary Zone

scholarly journals Characterization of S-Triazine Herbicide Metabolism by a Nocardioides sp. Isolated from Agricultural Soils

2000 ◽  
Vol 66 (8) ◽  
pp. 3134-3141 ◽  
Author(s):  
Edward Topp ◽  
Walter M. Mulbry ◽  
Hong Zhu ◽  
Sarah M. Nour ◽  
Diane Cuppels
Keyword(s):  
Agricultural Soils ◽  
Sole Source ◽  
Bacterial Strains ◽  
Corn Production ◽  
Whole Cells ◽  
Carbon And Nitrogen ◽  
Cell Extracts ◽  
Hydrolytic Reaction ◽  
Central Canada

ABSTRACT Atrazine, a herbicide widely used in corn production, is a frequently detected groundwater contaminant. Nine gram-positive bacterial strains able to use this herbicide as a sole source of nitrogen were isolated from four farms in central Canada. The strains were divided into two groups based on repetitive extragenic palindromic (rep)-PCR genomic fingerprinting with ERIC and BOXA1R primers. Based on 16S ribosomal DNA sequence analysis, both groups were identified as Nocardioides sp. strains. None of the isolates mineralized [ring-U-14C]atrazine. There was no hybridization to genomic DNA from these strains usingatzABC cloned from Pseudomonas sp. strain ADP or trzA cloned from Rhodococcus corallinus. S-Triazine degradation was studied in detail inNocardioides sp. strain C190. Oxygen was not required for atrazine degradation by whole cells or cell extracts. Based on high-pressure liquid chromatography and mass spectrometric analyses of products formed from atrazine in incubations of whole cells with H2 18O, sequential hydrolytic reactions converted atrazine to hydroxyatrazine and then to the end productN-ethylammelide. Isopropylamine, the putative product of the second hydrolytic reaction, supported growth as the sole carbon and nitrogen source. The triazine hydrolase from strain C190 was isolated and purified and found to have a Km for atrazine of 25 μM and a V max of 31 μmol/min/mg of protein. The subunit molecular mass of the protein was 52 kDa. Atrazine hydrolysis was not inhibited by 500 μM EDTA but was inhibited by 100 μM Mg, Cu, Co, or Zn. Whole cells and purified triazine hydrolase converted a range of chlorine or methylthio-substituted herbicides to the corresponding hydroxy derivatives. In summary, an atrazine-metabolizingNocardioides sp. widely distributed in agricultural soils degrades a range of s-triazine herbicides by means of a novel s-triazine hydrolase.

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