Incorrect Statement About Haemerythrin

GUJARAT SET 2023

Pick out the incorrect statement(s) with reference to haemerythrin:

1. It is a haem iron protein.
2. It has a molecular weight of about 108000 dalton.
3. It serves as the oxygen carrier in some marine worms.
4. Deoxyhaemerythrin contains two low-spin Fe(II) atoms and oxyhaemerythrin contains two Fe(III) atoms.

• (A) 1 and 3 only
• (B) 2 only
• (C) 2 and 3 only
• (D) 1 and 4 only

Correct Answer: (D) 1 and 4 only

Explanation:

• Statement 1 is INCORRECT: Despite the name, Hemerythrin is a non-heme iron protein. It does not contain a porphyrin ring.
• Statement 2 is CORRECT: Hemerythrin usually exists as an octamer with a molecular weight in the range of ~108,000 Daltons.
• Statement 3 is CORRECT: It is found in marine invertebrates like sipunculids (peanut worms), brachiopods, and some annelids.
• Statement 4 is INCORRECT: In Deoxyhaemerythrin, the two Fe(II) centers are high-spin, not low-spin. In Oxyhaemerythrin, the iron atoms are indeed Fe(III) (antiferromagnetically coupled), but the description of the deoxy state in the statement is false.