The correct answer is (A) a-4; b-1; c-2; d-3.​

Vitamin C Matching

Vitamin C (ascorbic acid) serves as a cofactor for prolyl hydroxylase, an enzyme essential for hydroxylation of proline residues in collagen synthesis. This post-translational modification stabilizes the collagen triple helix, preventing conditions like scurvy.​

Vitamin K Matching

Vitamin K enables gamma-carboxylation of glutamate residues in prothrombin (factor II), which converts to thrombin during blood clotting. This modification allows calcium binding for coagulation factor activation on phospholipid surfaces.​

Vitamin A Matching

Vitamin A, as retinal, forms the chromophore of rhodopsin, the light-sensitive protein in rod cells responsible for vision. Light isomerizes 11-cis-retinal to all-trans-retinal, initiating the visual signal transduction cascade.​

Vitamin B1 Matching

Vitamin B1 (thiamine) forms thiamine pyrophosphate (TPP), a cofactor for pyruvate dehydrogenase in converting pyruvate to acetyl-CoA, linking glycolysis to the TCA cycle. Deficiency impairs energy metabolism, as seen in beriberi.​​

Option Analysis

• (A) Correct: Matches all pairs accurately based on biochemical roles.​

• (B) Incorrect: Swaps c (Vitamin A) with d; rhodopsin requires retinal, not pyruvate dehydrogenase.​

• (C) Incorrect: Misplaces a (Vitamin C) to rhodopsin and c to prolyl hydroxylase; functions do not align.​

• (D) Incorrect: Wrongly assigns a to pyruvate dehydrogenase and b to prolyl hydroxylase; ignores specific cofactors.​

Vitamin C prolyl hydroxylase, Vitamin K thrombin, Vitamin A rhodopsin, and Vitamin B1 pyruvate dehydrogenase matching is a key CSIR NET Life Sciences topic testing vitamin cofactor roles in proteins. This guide solves matching question Q.96 with biochemical details.

Core Matchings Explained

• Vitamin C (a) – Prolyl hydroxylase (4): Ascorbic acid acts as a cofactor for prolyl-4-hydroxylase in collagen hydroxylation, stabilizing the triple helix via hydroxyproline.​

• Vitamin K (b) – Thrombin (1): Enables post-translational gamma-carboxyglutamation of prothrombin, precursor to thrombin for coagulation.​

• Vitamin A (c) – Rhodopsin (2): Retinal binds opsin to form rhodopsin, enabling phototransduction in vision.​

• Vitamin B1 (d) – Pyruvate dehydrogenase (3): Thiamine pyrophosphate decarboxylates pyruvate in the PDH complex for acetyl-CoA production.​

Why Option A Wins for CSIR NET

Option (A) a-4, b-1, c-2, d-3 perfectly aligns vitamin functions with proteins, crucial for exams like CSIR NET. Others fail: (B) confuses vision and metabolism enzymes; (C) mismatches collagen and vision roles; (D) inverts cofactors entirely. [-20]

Exam Tips: Vitamins Proteins Matching

• Focus on cofactors: TPP for decarboxylases, retinal for pigments, ascorbate for hydroxylases, phylloquinone for Gla proteins.

• Recall deficiencies: Scurvy (Vitamin C), night blindness (A), bleeding (K), beriberi (B1).

• Practice similar MCQs for CSIR NET, NEET, GATE biotech sections.