Factors Governing the Rate of Enzyme-Catalyzed Reactions

Factors Governing the Rate of Enzyme-Catalyzed Reactions 

Factors that affect the rate of enzyme-catalyzed reactions include enzyme and substrate concentration, pH, temperature, and the presence of inhibitors, activators, co-enzymes, and prosthetic groups. 

The simplest enzymatically catalyzed reaction for converting substrate S into product P with the intermediate formation of an ES complex, is  

Michaehs and Menten assumed that equilibrium is attained rapidly among E, S, and ES with the effect of 

Provided that an excess of free substrate molecules is present, addition of more enzyme molecules to the reaction system increases the concentration of the ES complex and thus the overall rate of reaction. This accounts for the observation that the rate of reaction is generally proportional to the concentration of enzyme present in the system and is the basis for the quantitative determination of enzymes by measurement of reaction rates. Reaction conditions are selected to ensure that the observed reaction rate is proportional to enzyme concentration over as wide a range as possible. 

The overall reaction involving conversion of substrate (S) to product (P) with formation of the enzyme-substrate 

Schematic diagram of a lock and key relationship between an enzyme and its substrate. The shape of the active site is complementary to that of the substrate molecule. 

---