Question

Which enzyme is responsible for albinism?

• A. Beta-hydroxylase
• B. Pyruvate dehydrogenase
• C. Hydroxylase
• D. Tyrosinase

Hint:

Remember: Albinism is due to a tyrosinase deficiency — an enzyme vital for melanin biosynthesis. It’s a classic GPAT question from the Biochemistry section.

Answer 1

The Correct Option is D

• Albinism is a congenital disorder characterized by the partial or complete absence of melanin pigment in the skin, hair, and eyes.
• The biosynthesis of melanin occurs via the tyrosine metabolic pathway, in which the enzyme tyrosinase plays a central role. 
• Tyrosinase catalyzes the conversion of tyrosine to DOPA (dihydroxyphenylalanine) and then to dopaquinone, which are key steps in melanin production.
• Mutations in the tyrosinase gene (TYR) result in defective or absent enzyme activity, leading to oculocutaneous albinism type 1 (OCA1).
• This enzyme is copper-dependent and is found in melanocytes. 

Other options:

(a) Beta-hydroxylase — Involved in catecholamine biosynthesis (e.g., norepinephrine production).

(b) Pyruvate dehydrogenase — Part of carbohydrate metabolism; links glycolysis to the Krebs cycle. 

(c) Hydroxylase — General term for enzymes adding hydroxyl groups, but not specific to melanin synthesis.