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MBBS QUESTION #10323
Question 1
Many water-soluble B-vitamins function biochemically primarily as:
  • Structural components of the enzyme's active site with no catalytic role
  • Coenzymes or precursors of coenzymes required for the catalytic activity of specific enzyme systems✔️
  • Competitive inhibitors of enzyme activity
  • Exclusively allosteric inhibitors of metabolic enzymes
Correct Answer Explanation
Most B-vitamins (e.g., thiamine, riboflavin, niacin, pyridoxine, B12) are precursors of essential coenzymes (TPP, FAD, NAD+, PLP, methylcobalamin) required by specific enzymes for catalysis — explaining why their deficiency produces distinct metabolic and clinical syndromes tied to the affected enzymatic pathways.