BDS (2023-24 Batch) - May 2024 - Quiz 02

The general mechanism is that an enzyme acts by

• Increasing activation energy

• Reducing the activation energy

• Decreasing pH value

• Increasing the pH value

The coenzyme is

• Often a metal

• always a protein

• often a vitamin

• always an inorganic compound

Which of the following is produced with the combination of apoenzyme and coenzyme

• Enzyme product complex

• Enzyme substrate complex

• Prosthetic group

• Holoenzyme

Which one among them is the example of competitive inhibition of an enzyme?

• Cytochrome oxidase by cyanide

• Hexokinase by glucose-6-phosphate

• Succinic dehydrogenase by malonic acid

• Carbonic anhydrase by carbon dioxide

Answer explanation

The inhibition of succinic dehydrogenase by malonic acid is an example of the competitive inhibition of an enzyme. A competitive inhibitor looks like the substrate and binds to the enzyme's active site. The substrate is then barred from binding to the same active site as the enzyme. Malonate is a competitive inhibitor of succinate dehydrogenase: it binds to the enzyme's active sites without reacting, and therefore competes with succinate, the enzyme's regular substrate.

Blocking of enzyme action by blocking its active site is called as

• Allosteric inhibition

• Competitive inhibition

• Feedback inhibition

• Non-competitive inhibition