Question

Differentiate between Holoenzyme and apoenzyme.

Answer 1

Hint: Enzymes are the biological catalysts that catalyze various biochemical reactions and help to increase the rate of reactions in the body. They are made up of amino acid sequences and they are not consumed in the reaction.

Complete Answer:
- Apoenzyme- Protein part of the enzyme and coenzyme- the non-protein part. The combination of both apoenzyme and coenzyme together forms the functional enzyme which is known as Holoenzyme.
Apoenzyme- It is an inactive enzyme, which activates with the help of binding of an organic or inorganic cofactor. Cofactors are organic or inorganic molecules for example: $Zn^{+2}$, $K^{+2}$, $Mg^{+2}$.
Holoenzyme- These are the active forms of enzymes. Holoenzymes represent the apoenzyme bound to cofactors or prosthetic groups.

Sl.No	Holoenzyme	Apoenzyme
1.	Holoenzyme refers to the apoenzyme along with cofactor and also becomes catalytically active.	Apoenzyme refers to the inactive form of enzyme.
2.	Consists of the apoenzyme and several types of cofactors.Example: DNA polymerase and RNA polymerase are two holoenzymes which require magnesium ions to become active and initiate polymerization.	It consists of the protein part of the enzyme.Example: Catalytic components of DNA polymerase enzyme are called as apoenzymes. Common metal ions that bind with apoenzymes are Zinc, Calcium, Magnesium etc.

Note: If the cofactor is removed from the holoenzyme it will again be converted into apoenzyme which is inactive. Cofactor should be present at the active site of apoenzyme as they provide groups that protein part of any enzyme does not possess to catalyze the reaction.