Question

18. A key reaction in biosynthesis of thyroxine ſa hormone that regulates metabolic rate) is iodination of tyrosine residues in thyroglobulin via an electrophilic aromatic substitution reaction indicated below. Given that this reaction occurs under physiological pH in presence of water, apply your knowledge of chemistry of phenols to identify the non-aromatic intermediate expected to form in this reaction. protein protein protein protein H2O + 1-OH OH hypolodous acid он a tyrosine residue in thyroglobulin an iodinated tyrosine residue in thyroglobulin (a precursor to thyroxine) protein protein protein protein protein ZN. protein protein protein protein protein | protein protein ULOH нон 19 он (A) (B) (C) (D)

Answer 1

Q18. Here, The I⁺ will attack to Ortho position of -OH group. Further, oxygen will donate electrons to the carbon attached to it. As, can be seen in the attached figure, the answer will be (A)

NH (A) B = Protein

Q14 Here, all intermediates except intermediate (B) can be formed. Please see the attached figure. The reaction proceeds by attack of Nitrogen on Carbonyl Carbon, followed by elimination of water. Thus, the answer will be (B)

swn to CA Total Nu o I ut attack on - oh ina - 1 - 420 40 CE