(7.3 marks) b) Shown below is the chemical structure of the amino acid tryptophan. COOH tryptophan HN NH2 () Explain why
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- 7 3 Marks B Shown Below Is The Chemical Structure Of The Amino Acid Tryptophan Cooh Tryptophan Hn Nh2 Explain Why 1 (122.38 KiB) Viewed 40 times
(7.3 marks) b) Shown below is the chemical structure of the amino acid tryptophan. COOH tryptophan HN NH2 () Explain why the indole component of tryptophan is aromatic. (ii) Tryptophan has two pKa values (pKai = 2.8, pKa2 = 9.4) and its isoelectric point (pl) is 5.9. Explain what is meant by the underlined term. Draw the predominant chemical structure of tryptophan when the pH of a solution of the amino acid matches the value of the pl of the substance. Explain why you chose that particular structure. Draw the predominant structure of tryptophan as it would exist at (a) pH 2 and (b) pH 10. Explain your answers, (ii) What is a peptide bond? Explain why tryptophan can form two peptide bonds to two other amino acids. Illustrate your answer with suitable chemical structures, (10 marks) Page 12 of 17