Cosolutes Modify Alkaline Phosphatase Catalysis through Osmotic Stress and Crowding Mechanisms.

Examining the effects of different cosolutes on enzyme kinetics yielded glimpses into their potential behavior when functioning in their natural, complex, milieu. Viewing cosolute influences on a model enzyme, calf intestinal alkaline phosphatase, as a combination of competitive and uncompetitive behaviors provided quantitative insights into their effects on catalysis. Observed decreases in the apparent specificity constant, , caused by the presence of polyethylene glycols or betaine in the reaction solution, indicated interference with enzyme-substrate complex formation.