Purification and properties of a novel extra-cellular thermotolerant metallolipase of Bacillus coagulans MTCC-6375 isolate

摘要

A novel extra-cellular lipase from Bacillus coagulans MTCC-6375 was purified 76.4-fold by DEAE anion exchange and Octyl Sepharose chromatography. The purified enzyme was found to be electrophoretically pure by denaturing get electrophoresis and possessed a molecular mass or approximately 103 kDa. The lipase was optimally active at 45 degrees C and retained approximately 50% of its original activity after 20 min Of incubation at 55 degrees C. The enzyme was optimally active at pH 8.5. Mg2+, Cu2+, Ca2+, Hg2+, Al3+, and Fe3+ at 1 mM enhanced hydrolytic activity of the lipase. Interestingly, Hg2+ ions resulted in a maximal increase in lipase activity but Zn2+ and Co2+ ions showed ail antagonistic effect on this enzyme. EDTA at 150 mM concentration inhibited the activity of lipase but Hg2+ or Al3+ (10 mM) restored most of the activity of EDTA-quenched lipase. Phenyl methyl sulfonyl fluoride (PMSF, 15 mM) decreased 98% of original activity of lipase. The lipase was more specific to p-nitrophenyl esters of 8 (pNPC) and 16 (pNPP) carbon chain length esters. The lipase had a V-max and K-m of 0.44 mmol mg(-1) min(-1) and 28 mM for hydrolysis of pNPP, and 0.7 mmol mg(-1) min(-1) and 32 mM for hydrolysis of pNPC, respectively. (c) 2005 Elsevier Inc. All rights reserved.