What does Kcat represent in enzyme kinetics?

Kcat, often referred to as the turnover number, represents the maximum number of substrate molecules converted to product by an enzyme per unit time, when the enzyme is fully saturated with substrate. This means that Kcat reflects the rate-limiting step in the enzymatic reaction under these conditions, making it a crucial parameter in understanding an enzyme’s catalytic efficiency.

Knowing that Kcat provides insight into how efficiently an enzyme can process a substrate allows researchers to compare the performances of different enzymes. This measure is significant in enzyme kinetics because it conveys how quickly an enzyme can convert substrate into product when there is more substrate present than the enzyme can process at once, a state of saturation. Understanding Kcat helps in characterizing enzyme mechanisms and is vital for applications in biochemistry and drug design.