Water miscible mono alcohols' effect on the proteolytic performance of Bacillus clausii serine alkaline protease
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In this study, our investigations showed that the increasing concentrations of all examined mono alcohols caused a decrease in the V m, k cat and k cat/K m values of Bacillus clausii GMBE 42 serine alkaline protease for casein hydrolysis. However, the K m value of the enzyme remained almost the same, which was an indicator of non-competitive inhibition. Whereas inhibition by methanol was partial non-competitive, inhibition by the rest of the alcohols tested was simple non-competitive. The inhibition constants (K I) were in the range of 1.32-3.10 M, and the order of the inhibitory effect was 1-propanol>2-propanol>methanol>ethanol. The ΔG ≠ and ΔG ≠ E - T values of the enzyme increased at increasing concentrations of all alcohols examined, but the ΔG ≠ ES value of the enzyme remained almost the same. The constant K m and ΔG ≠ ES values in the presence and absence of mono alcohols indicated the existence of different binding sites for mono alcohols and casein on enzyme the molecule. The k cat of the enzyme decreased linearly by increasing log P and decreasing dielectric constant (D) values, but the ΔG ≠ and ΔG ≠ E - T values of the enzyme increased by increasing log P and decreasing D values of the reaction medium containing mono alcohols. © 2013 Springer Science+Business Media New York.