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Pak. J. Bot., 42(5): 3507-3516, 2010. |
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Updated: 06-12-10 | ||||
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KINETICS AND THERMODYNAMIC STUDIES OF ALPHA AMYLASE FROM BACILLUS LICHENIFORMIS MUTANT
IKRAM-UL-HAQ*, MUHAMMAD MOHSIN JAVED, UZMA HAMEED AND FAZAL ADNAN
Abstract: The present investigation deals with the purification and characterization of enzyme α-amylase from a mutant strain of Bacillus licheniformis EMS-6. A laboratory scale stirred fermentor of 7.5 L capacity was used for the enzyme production under optimal conditions. The enzyme was purified up to homogeneity level by Ammonium sulphate and ion-exchange chromatography using a fast protein liquid chromatography (FPLC) system. The specific activity of the enzyme increased 4-5 times while the yield was found to be 40.4%. The purification fold by RESOURCE-S was recorded to be 3.58. The molecular weight was found to be 55 KDa. In the present research work, the Vmax (2778 U/mg/min) and Km (8.3mg/ml) of α-amylase were derived from the Lineweaver Burke plot. Thermodynamic parameters for soluble starch hydrolysis, Ea, ΔH, ΔS and ΔG of α-amylase from B. licheniformis EMS-6 were found to be 25.14 KJ/mol, 22.53 KJ/mole, -110.95J/mole/K and 36968 J/mole, respectively. The enzyme was stable over a pH range of 4.5-9.0 and gave pH optimum of 7.0. The pKa1 and pKa2 of ionizable groups of active site controlling Vmax, determined by Dixon plot, were 6.0 and 7.5, respectively.
Institute of Industrial Biotechnology (IIB), GC University Lahore, Pakistan |
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