Thiol-dependent serine alkaline proteases from Bacillus sp. HR-08 and KR-8102

• Published in: Applied biochemistry and biotechnology Vol. 134; no. 1; pp. 77 - 87
• Main Authors: Moradian, F, Khajeh, K, Naderi-Manesh, H, Ahmadvand, R, Sajedi, R.H, Sadeghizadeh, M
• Format: Journal Article
• Language: English
• Published: 01.07.2006
• Subjects: alkalinity; Bacillus; Bacillus (bacteria); calcium; dithiothreitol; enzyme activity; enzyme inactivation; enzyme inhibition; half life; hydrogen peroxide; iodoacetic acid; iron; magnesium; manganese; phenylmethylsulfonyl fluoride; proteinase inhibitors; provenance; serine proteinases; soil bacteria; strains; surfactants; temperature; thiols; Iran
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1385/ABAB:134:1:77

Two Bacillus sp. strains, HR-08 and KR-8102, isolated from soil of the west and north parts of Iran were screened on gelatin agar medium for their ability to produce alkaline protease. The enzymes were active in a wide pH range (6.0-11.0) and stable in the alkaline range (7.0-12.0). The optimum temperatures for the protease from HR-08 and KR-8102 were 65 and 50°C, respectively. The irreversible thermoinactivation of HR-08 and KR-8102 proteases showed that the stability of HR-08 enzyme was higher than that of KR-8102 and the half-lives of these enzymes were 95 and 32 min at 50°C, respectively. In the presence of 10 mM Ca2+, HR-08 retained 100, 90, and 20% of its initial activity after heating for 30 min at 50, 60, and 70°C, respectively. Enzymes were inhibited by phenylmethylsulfonyl fluoride and iodoacetate. After inhibition by iodoacetate, both enzymes were reactivated by dithiothreitol. These data show that the enzymes seem to be thiol-dependent serine alkaline proteases. The enzymes especially from HR-08 were stable in the presence of H2O2, surfactants, and local detergents; their activities were enhanced in the presence of 5 mM Fe2+; and the presence of 5mM metal ions such as Mg2+, Cu2+, and Mn2+ produced almost no effect.