Question

1. Identify the amino acids in the following tripeptide and provide the major structure of the tripeptide at pH 3, 7, 12. H O ?? ?? 2a. Ideally, one could synthesize a peptide without the use of protecting groups In the following problem, provide a mechanism for the synthesis of the dipeptide Phe-Trp. Assume that the only product formed is Phe-Trp. N-C-N Ph (DCC) OH Phe-Trp

Answer 1

Answer 1): Lysine NH3 NH Proline Tryptophan H@H O он он at pH 3 amino groups of proline and lysine side chain will be protonated at acidic pH 3 NH2 NH2 он at pH 7 At neutral pH all amino acid residue will be uncharged at pH12 -COOH group of tryptophan will be ionised to -CoO at basic pH 12