Question

Apoenzyme is a
a. Protein
b. Carbohydrate
c. Vitamin
d. Amino acid

Answer 1

Hint: An enzyme is a biochemical produced in our body which helps in the catalysis of a biochemical reaction. It is mainly proteinaceous except for Ribozymes.

Complete answer:
Apoenzyme is a protein.
An apoenzyme is an inactive enzyme, activation of the enzyme occurs upon binding of an organic or inorganic molecule known as a cofactor. For example, the enzyme ‘pyruvate dehydrogenase' has five cofactors namely, TPP, FAD+, NAD, CIA, and Magnesium.
Apoenzyme along with its cofactor is known as a ‘Holoenzyme'.

Additional Information: ‘Cofactor' is a non-protein molecule that assists apoenzyme in bringing about a metabolic reaction.

Types of cofactor are:
- Organic cofactors – Examples:- Vitamin B3, Flavin, ATP, etc.
- Inorganic cofactors or Minerals- Examples:-
Zn is a cofactor of Alcohol dehydrogenase and Carbonic Anhydrase
Nickel is a cofactor of Urease.
Copper acts as a cofactor of Cytochrome oxidase.

Organic cofactors are further divided into two groups-
- Coenzyme- These remain loosely bound to the enzyme.
- Prosthetic group- They bound tightly to the enzyme.

Note:
- The inactive form of the apoenzyme is known as a proenzyme or zymogen.
- The proenzyme may contain several extra amino acids in the protein structure which are removed leading to a final specific tertiary structure to be formed before it is activated as an apoenzyme.
- The cofactor TPP stands for Thiamine Pyrophosphate.