Question

Which of the following enzyme(s) has/have heme as a prosthetic group?
(i) Catalase
(ii) Carboxypeptidase
(iii) Succinic dehydrogenase
(iv) Peroxidase

• A. (i) only
• B. (i) and (ii)
• C. (ii) and (iii)
• D. (i) and (iv)

Answer 1

The correct option is D (i) and (iv)

Enzymes are also known as biocatalysts. These can be simple or conjugated. Conjugated enzymes are those which consist of protein part along with non-protein counterpart helping in catalytic activity. The protein part of the enzyme comprises the apoenzyme which is functionally inactive. The non-protein part is known as cofactor.

Protein part + non-protein component = holoenzyme

Holoenzyme is the functionally active form of enzyme.

Prosthetic groups are a type of cofactor which gets firmly attached to apoenzymes. One of the examples is heme. Heme is an iron-containing prosthetic group present in cytochromes, haemoglobin, myoglobin, catalase and peroxidase.