Question

What is the value of K, when enzyme has a Km of 1 mM in the absence of a competitive inhibitor and an apparent KM of 3 mM in the presence of 10 mM of the inhibitor?

a) 0.3 μM
b) 3 mM
c) 10 uM
d) 5 μM

Answer 1

The value of K, the inhibition constant for the enzyme with an apparent Km of 3 mM in the presence of 10 mM of a competitive inhibitor, where the original Km is 1 mM, is 5 mM.

Step-by-step explanation:

The value of K, or the inhibition constant, can be determined using the relationship between the Michaelis constant (Km) in the absence and presence of a competitive inhibitor. The Michaelis-Menten equation gives an insight into the enzyme kinetics and the impact of inhibitors on enzyme activity. In the presence of a competitive inhibitor, the apparent Km is given by the equation Km(apparent) = Km(1 + [I]/K), where [I] is the concentration of the inhibitor. We can rearrange this equation to solve for K when the apparent Km and the inhibitor concentration are known.

Using the given values, where Km is 1 mM without the inhibitor and the apparent Km is 3 mM with 10 mM of the inhibitor, we have 3 mM = 1 mM (1 + [10 mM]/K). Thus, after rearranging and solving for K, we find that K = 10 mM / (3 - 1), which simplifies to K = 5 mM.