Question

1. Binding energy between an enzyme and a substrate contributes to catalysis in which way?

A. Binding energy provides the enzyme specificity for the substrate

B. binding energy contributions allow for entropy reduction in the substrate-enzyme complex

C. binding energy compensates for energy changes as a result of desolvation of the substrate

D. binding energy contributes to the process of induced fit between the substrate and the enzyme

E. all of the above are correct

2. a reaction is spontaneous if..

A. the transition state has higher free energy that the substrate

B. the product has lower free energy that the substrate

C. it proceeds rapidly and without a catalyst

D. it can proceed in only on direction

3. the enzyme Pepsin is produced in the stomach lining initially as a _______, which requires _______ for activation in the stomach.

A. Kinase; phosphorylation

B. zymogen; irreversible proteolytic cleavage

C. proprotein; reversible proteolytic cleavage

D. zymogen; ubiquitination

E. phosphorylase; irreversible proteolytic cleavage

Answer 1

Ans. 1.

(E) is correct, i.e. All the statements are true.

Explanation - When substrate interacts with enzyme, the energy derived from this interaction is called as Binding energy and this energy is specific for binding of specific substrate to the respective enzyme. Indeed Binding energy is reponsible for induced fit between substrate and enzyme. Entropy reduction is one of the pros of Binding energy where there is a large reduction in the relative motions of two substrates that are to react. It also compensates for energy changes as a result of desolvation of the substrate.

Ans. 2.

(C) is the correct option.

Ans. 3.

(B) is the correct answer.

Explanation - Pepsin is the active form and is secreted in the inactive form, known as Zymogen i.e. Pepsinogen. The Pepsin enzyme is responsible for proteolytic clevage that is to break down the proteins and digest them.