Differential effect of a chemical denaturant on activity and stability of a serine protease in nonaqueous media

With reference to industrial application, reusability of the biocatalyst is an important criterion which determines the cost of the final product. Urea-induced structural perturbation of proteases has led to higher enzymatic activity, especially in nonaqueous media. The mechanism behind this phenomenon has not been investigated in detail. Using the transesterification activity of subtilisin Carlsberg in nonaqueous media as an illustration, we report that the higher activity is due to simultaneous decrease in Michaelis constant and increase in turnover number of the enzyme. However, we show that this perturbed architecture is unable to retain the high activity-conformation for further rounds of catalysis. Thus, we conclude that the use of an enzyme for commercial applications is dependent upon a compromise between activity and (operational) stability.