Question

Holoenzyme is the complete enzyme consisting of an apoenzyme and a co-factor. Select the option that correctly identifies the nature of apoenzyme and co-factor.

	Apoenzyme	Co-factor
(a)	Protein	Non-protein
(b)	Non-protein	Protein
(c)	Protein	Protein
(d)	Non-protein	Non-protein

• A. a
• B. b
• C. c
• D. d

Answer 1

Answer: (A)

Enzymes may be broadly classified into two types depending on their chemical composition - simple enzymes and conjugated enzymes. Simple enzymes are wholly made up of proteins and any additional substance or group is absent, e.g., pepsin, trypsin, etc. Conjugated enzymes (or holoenzymes) are formed of two parts - a protein part called apoenzyme and a non-protein part named co-factor. The complete conjugated enzyme consisting of an apoenzyme and a co-factor is called holoenzyme. Holoenzyme is the functional unit of enzyme.
$\underset{\text{(Active enzyme)}}{\text{Holoenzym}} \longrightarrow \underset{\text{(Protein part)}}{\text{Apoenzyme}} + \underset{\text{(Non-protein part)}}{\text{Co-factor}}$
Co-factor may be inorganic or organic in nature. Catalytic activity is lost when co-factor is removed from the enzyme which indicates that it plays a crucial role in catalytic activity of enzymes.