Question

Explain how the Kd of an enzyme for substrate binding is related to its Km value and how enzymatic turnover can lead to an increase in the concentration of free enzyme at constant substrate concentration.

Answer 1

Km is related to subtrate binding strength, greater the substrate binding to enzyme is, lower would be the value of Km. Similarly a weak enzyme-substrate complex means high Km. It is related to kinetic of the reaction. So at lower

Kd relates to thermodynamic enzyme-substrate binding and release in the actual completed reaction, which is not always the case. A short reaction time may give Km value but not Kd value. High enzyme turnover means the substrate binding to enzyme is not strong so Km would be low for such a process but a high vaue for Kd would be seen in this reaction as the rate of conversion of substrate to product directly relates to Kd.