The correct answer is (2) A-(ii), B-(i), C-(iv), D-(iii).

Introduction

Coenzymes are vital non-protein molecules that partner with enzymes to catalyze a wide range of biological reactions. They often serve as temporary carriers of functional groups, atoms, or electrons, facilitating crucial transformations in cellular metabolism. Mastery of which coenzyme transfers which group is essential for biochemistry, physiology, and exam success.

Detailed Coenzyme Functions and Their Matched Groups

Column-Wise Analysis

How These Coenzymes Work

Coenzyme A (Acyl Group Carrier)

• Contains a reactive thiol (-SH) group that forms high-energy thioester bonds with acyl groups.

• Central to the citric acid cycle, fatty acid metabolism, and synthesis of essential biomolecules.

FAD (Electron Carrier)

• Accepts and donates electrons during redox reactions as part of flavoproteins.

• Integral in the mitochondrial electron transport chain for ATP generation.

Pyridoxal Phosphate (Amino Group Carrier)

• Acts as a coenzyme in enzymes involved in amino acid catabolism and transformation.

• Forms a Schiff base with substrate amino acids, enabling transfer of amino groups between molecules.

NAD/NADP (Hydride Ion Carrier)

• Functions as electron transporter via hydride transfer in metabolic pathways.

• Shuttles reducing equivalents from catabolic to anabolic pathways—a core of metabolic regulation.

Importance in Metabolic Pathways

• Coenzyme A enables the transfer and activation of carbon fragments for synthesis and breakdown.

• FAD and NAD (and their reduced/oxidized forms) maintain the flow of electrons and fuel energy conversion.

• Pyridoxal phosphate ensures the versatile modifications needed for protein and nitrogen metabolism.

• The specific chemical group transfer capability of each coenzyme is vital for metabolic efficiency and regulation.

Clinical and Research Applications

• Vitamin deficiencies manifest as metabolic blockages due to impaired coenzyme function (e.g., B vitamin deficiency syndromes).

• Drug design: Inhibitors often target coenzyme binding sites for disease treatment.

• Diagnostic tests measure coenzyme activities to assess metabolic and organ health.

Table Summary: Correct Matches

Conclusion

The functional matching of coenzymes with their respective transient chemical group transfers is fundamental in understanding enzyme-catalyzed metabolic processes.

• Coenzyme A: Acyl groups (A-ii)

• FAD: Electrons (B-i)

• Pyridoxal phosphate: Amino groups (C-iv)

• NAD: Hydride ions (D-iii)

This knowledge anchors advanced studies in biochemistry, supports clinical diagnostics, and is critical for success in life sciences and medical examinations.