Step 1: Understanding the Concept:
Coenzymes are small, organic non-protein molecules that temporarily associate with enzymes to assist in their catalytic activity.
Many coenzymes are derived from water-soluble vitamins.
They function primarily as transient carriers of specific chemical groups, atoms, or electrons transferred during enzymatic reactions.
Understanding the specific transfer roles of major coenzymes is a core aspect of biochemistry and cellular metabolism. Step 2: Detailed Explanation:
Let us match each coenzyme with its corresponding chemical group transfer role:
(A). Coenzyme A (CoA-SH) \(\rightarrow\) (IV) Acyl groups:
Coenzyme A, derived from vitamin \(\text{B}_5\) (pantothenic acid), contains a reactive thiol group.
It serves as a key carrier of acyl groups, forming high-energy thioester bonds (as seen in Acetyl-CoA during the Krebs cycle and fatty acid metabolism).
Thus, (A) matches with (IV).
(B). Flavin Adenine Dinucleotide (FAD) \(\rightarrow\) (III) Hydrogen atoms:
FAD, derived from vitamin \(\text{B}_2\) (riboflavin), is a major electron carrier.
It undergoes reversible reduction, accepting two electrons and two protons (equivalent to two hydrogen atoms) to form \(\text{FADH}_2\) during redox reactions.
Thus, (B) matches with (III).
(C). Pyridoxal Phosphate (PLP) \(\rightarrow\) (II) Amino group:
PLP, derived from vitamin \(\text{B}_6\) (pyridoxine), is the coenzyme required for all transamination reactions.
It temporarily accepts and transfers amino groups between amino acids and keto acids.
Thus, (C) matches with (II).
(D). Thiamine Pyrophosphate (TPP) \(\rightarrow\) (I) Aldehyde group:
TPP, derived from vitamin \(\text{B}_1\) (thiamine), is involved in decarboxylation reactions.
It stabilizes and transfers activated aldehyde/ketone intermediates (such as hydroxyethyl groups in pyruvate dehydrogenase).
Thus, (D) matches with (I).
Combining these pairings: (A) - (IV), (B) - (III), (C) - (II), (D) - (I).
This matches option (B) (note that option (D) is printed identically to (B) in the exam paper, both representing the correct sequence). Step 3: Final Answer:
Therefore, the correct match is represented by option (B).
