title: Purification and properties of extracellular carboxyl proteases of acid-tolerant bacteria, isolated from compost.
abstract: Four strains of acid-tolerant and protein-using bacteria were isolated from compost. Two of them, Gram-negative strains MB8 and MB11, were identified as a new genus close to Stenotrophomonas species MB8 and Burkholderia species MB11, respectively. Both bacteria produced extracellular carboxyl proteases (CP) in acid-casein-starch medium. The enzymes, termed CP MB8 and CP MB11, purified through ion exchange and gel filtration chromatographies had molecular weights of 61,000 (CP MB8) and 36,000 (CP MB11) as estimated by SDS-PAGE, and showed optimum activities with hemoglobin as a substrate at pH 3.5 (CP MB8) and pH 3.7 (CP MB11) at 55 degrees C. Both of the enzymes were not inhibited by pepstatin, DAN, or EPNP. These results suggest that both enzymes are members of the pepstatin-insensitive carboxyl proteinase family (EC 3.4.23.33), except for a larger molecular weight of the CP MB8 enzyme.
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan. takehana@chem.agr.hokudai.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Takehana
authors.forename: S
authors.initials: S
authors.lastname: Inoue
authors.forename: R
authors.initials: R
authors.lastname: Takei
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.forename: H
authors.initials: H
authors.lastname: Matsui
authors.forename: M
authors.initials: M
authors.lastname: Honma
mesh_terms: D000595:Amino Acid Sequence; D002268:Carboxypeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D016946:Gram-Negative Aerobic Rods and Cocci / Q000201:enzymology* / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D020560:Proteobacteria / Q000201:enzymology* / Q000254:growth & development; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012988:Soil Microbiology
chemical_list: D010446:Peptide Fragments; D002268:Carboxypeptidases