Question

Non-protein part of enzyme is called
a. Prosthetic group
b. Active site
c. Cofactor
d. Catalytic agent

Answer 1

Enzymes are the biocatalysts that catalyse the biochemical reactions in the living cells. They are proteinaceous in nature. Enzymes have a complex molecular organization. Enzymes are organic catalysts and there are some inorganic catalysts which are not found in living cells.

Complete answer:
Enzymes are found in the living cells of plants and animals. Enzyme catalyses only specific reactions. They are highly efficient. Enzymes contain active sites. An active site is a pocket or crevice into which the substrate fits.

Enzymes are proteinaceous in nature but there are two RNA enzymes which are not proteinaceous in nature: Ribozyme and Ribonuclease – P. Enzymes do not start a chemical reaction but increase the rate of chemical reaction. Enzymes are highly specific in their action.

Cofactors are the non-protein part of the enzyme. The enzymes are highly catalytic but many enzymes exhibit the catalytic activity only in association with certain non-protein substances. Such a substance is known as cofactors. Enzymes the protein part is known as apoenzyme.

There are three types of cofactors:
- Prosthetic group: They are the organic compound and are tightly bound to the apoenzyme.
- Coenzymes: The association of co-enzymes with apoenzyme lasts for a short period of time.
Metal ions: There are many enzymes that require metal ions for their activity.

Hence, the correct answer is option (C).

Note: Catalytic activity is lost when the cofactor is removed from the enzyme which testifies that they play a very important role in the catalytic activity of the enzyme. There are multi-molecular forms of enzymes which are synthesized by different genes present in the same organisms known as iso-enzymes. There are 100 iso-enzymes present till now.