Dear colleagues,
There are two important concepts in enzyme kinetic, Km (Michaelis Constant in Michaelis-Menten equation) and Kcat (Catalytic Constant or Molecular activity). So, I need to know, according to their equation, what is the relationship between Km and Kcat?
Sincerely yours, Homayoon.
Hi....
Km; The second order rate constant kcat/Km indicates the catalytic efficiency. of the enzyme: A direct measure of the efficiency of the enzyme in transforming Subst. kcat/Km combines: the effectiveness of transformation of bound product.
According to the steady-state approximation introduced by Briggs and Haldane in 1925, the concentration of the enzyme-substrate complex, [ES], remains constant as the overall process catalyzed by the enzyme E occurs.
E + S ES => E + P
Where the rate constant of the second reaction is kcat (also called k2 by classical texts of Biochemistry). This approach established a more general definition of the KM that raises the relationship between KM and kcat:
KM = (k-1 + kcat)/k1
This equation can be expressed as KM = k-1/k1 + kcat/k1, and since k-1/k1 is a constant that is usually symbolized as Ks, then KM can alternatively be expressed as
KM = Ks + kcat/k1
It can be seen then that the KM is greater in the measure that the kcat is bigger. Otherwise, when kcat
Dear Jose,
Thanks for your thorough answer.
Sincerely yours, Homayoon.
Hi, I'm my tendency to physiology and I do not know about your question.
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Enzymology
- Enzymes