title: Characterization of detergent compatible protease of a halophilic Bacillus sp. EMB9: differential role of metal ions in stability and activity.
abstract: A moderately halophilic protease producer, Bacillus sp. strain isolated from sea water is described. The protease is purified to homogeneity by ammonium sulphate precipitation and CM cellulose chromatography. The serine protease has a molecular mass of 29 kDa. Enzymatic characterization of protease revealed K(m) 2.22 mg mL(-1), Vmax 1111.11 U mL(-1), pH optimum 9.0, t1/2 190 min at 60°C and salt optima 1% (w/v) NaCl. The protease is remarkably stable in hydrophilic and hydrophobic solvents at high concentrations. The purified preparation is unstable at room temperature. Ca(2+) ions are required for preventing this loss of activity. Interestingly, the activity and stability are modulated differentially. Whereas, divalent cation Ca(2+) are involved in maintaining stability in solution at room temperature by preventing unfolding, monovalent Na(+) and K(+) ions participate in regulating the activity and assist in refolding of the enzyme. Application of the protease is shown in efficient removal of blood stain.
authors.affiliation: Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, New Delhi, India.
authors.forename: Rajeshwari
authors.initials: R
authors.lastname: Sinha
authors.forename: S K
authors.initials: SK
authors.lastname: Khare
mesh_terms: D000645:Ammonium Sulfate; D001407:Bacillus / Q000201:enzymology*; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D011232:Chemical Precipitation; D002942:Circular Dichroism; D003902:Detergents / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D007194:India; D007700:Kinetics; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013696:Temperature; D013816:Thermodynamics
chemical_list: D003902:Detergents; D012336:RNA, Ribosomal, 16S; D010447:Peptide Hydrolases; D000645:Ammonium Sulfate; D002118:Calcium