Water Miscible Mono Alcohols' Effect on the Proteolytic Performance of Bacillus clausii Serine Alkaline Protease

Abstract

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 Delta G (not equal) and Delta G (not equal) (E -aEuro parts per thousand T) values of the enzyme increased at increasing concentrations of all alcohols examined, but the Delta G (not equal) (ES) value of the enzyme remained almost the same. The constant K (m) and Delta G (not equal) (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 Delta G (not equal) and Delta G (not equal) (E -aEuro parts per thousand T) values of the enzyme increased by increasing log P and decreasing D values of the reaction medium containing mono alcohols.