The picture below shows the results of trypsin digestion of

Last updated: 10/6/2023

The picture below shows the results of trypsin digestion of a peptide How do we know immediately from the results of the digestion that the C terminus of the original protein is tyrosine N Asp Ala G Arg Hi Cys Lys Trp Lys Ser Gau Asn Leu lke Arg Thr Tyr c Alp Ab Gly Arg Hi Cy Lys Trp Las Trypsin Set Clu Asn Leu lle Arg Thr Tyr O Tyrosine is confirmed by chymotrypsin to be the C terminus O Trypsin is specific for basic amino acids leaving them as the C terminus of peptides it generates therefore if a tyrosine is the C terminus of a fragment it was not generated by trypsin Trypsin always leaves tyrosine as the C terminus when it cleaves peptides O The premise of the question is incorrect From the available trypsin digest data we do not know that tyrosine is the C terminus O Tyrosine is always the C terminus of a protein