GATE 2026 CY – Question 55

The correct statement(s) about enterobactin (ent) is(are)

Show answer and explanation

Correct answer: (A) It has three catechol moieties; (B) It has a serine-trilactone backbone; (C) It binds with Fe3+ ion to form [Fe(ent)]3− ion

Explanation

**Enterobactin** is the siderophore produced by *E. coli* to capture iron.

**A. It has three catechol moieties.** True. It carries three 2,3-dihydroxybenzoyl (catecholate) arms. ✓
**B. It has a serine trilactone backbone.** True. The three catechol arms are attached through amide bonds to a cyclic trimer of L-serine (a 12-membered triester ring). ✓
**C. It binds Fe³⁺ to form $[\text{Fe(ent)}]^{3-}$.** True. The six catecholate oxygen atoms (each deprotonated, six negative charges in total) bind Fe(III), giving a complex of charge $+3-6=-3$. ✓
**D. It has three hydroxamic acid groups.** False. Hydroxamate siderophores (such as desferrioxamine) have these; enterobactin uses catecholates.

Answer **A, B and C**.