Question

Biochemistry

a. What is an "apparent Km"?

b. What is K_I?

c. What is a? (in the context of enzyme inhibition equations!)

d. What is the difference between reversible and irreversible inhibitors? In what category does competitive, uncompetitive and mixed inhibition belong?

e. What is a suicide inhibitor (or suicide inactivator)? Why would this type of inhibition also be called “mechanism-based inactivators”?

Answer 1

ANS. a. Apparent Km is the Michaelis constant observed under certain conditions like in the presence of a competitive inhibitor, hinders the determination of its actual or original value.

ANS. b. KI in biochemistry is the inhibitor's concentration at which under saturating substrate conditions makes the rate of the reaction half of the maximum reaction rate i.e. Vmax.

ANS. d. In the case of Irreversible inhibitors, the decomposition of the enzyme-inhibitor complex is very slow because the inhibitor is tightly bound to the targeted enzyme and the reaction is irreversible.

in the case of reversible inhibitors, the decomposition of the enzyme-inhibitor is rapid and the reaction is reversible.

ANS. e. Suicide inhibition or suicide inactivation is an irreversible reaction when an enzyme binds to a substrate analog via covalent interactions during the normal catalysis reaction.