Question

(a) What is an enzyme?
(b) Give an example of apoenzyme.
(c) Give an example of the coenzyme.

Answer 1

Hint: All the enzymes are protein molecules while apoenzyme is an inactive enzyme and activation of this enzyme occurs upon binding of an organic non-protein molecule known as Coenzyme.

Complete answer:
(a) Enzymes are protein molecules in cells which work as biological catalysts in our body. Enzymes increase chemical reactions in the body, but do not get used up in the process, therefore can be used again and again.
Almost all biochemical reactions in living things need enzyme molecules. With an enzyme, chemical reactions in our body go much faster than they would without the enzyme. Other biological catalysts are catalytic RNA molecules, known as ribozymes.
The substances which present at the start of a reaction are called substrates. The substances present at the end of a reaction are called products. Enzymes work on the substrates, and convert them into products.

(b) Example of apoenzyme is apo glucose oxidase.

(c) Examples of coenzymes are the B vitamins and S-adenosylmethionine.

Additional information:
The study of enzymes is called enzymology.
In 1833, the first enzyme was found by Anselme Payen.

Note:
- Many enzymes require an additional molecule, known as a cofactor to increase the catalytic activity. Cofactors are non-protein molecules that carry out those chemical reactions that cannot be performed by the standard 20 amino acids. Cofactors can be either inorganic molecules (metals) or organic molecules (coenzymes).
- Coenzymes are small organic molecules that are non-proteins and mostly derivatives of vitamins, they themselves bind to the apoenzyme protein molecule to produce an active holoenzyme or conjugate enzyme.