With reference to the following peptide: (a) Identify the N-terminal and Cterminal amino acids. (b) Name the peptide using one-letter abbreviations. (c) Label all the amide bonds in the peptide backbone.

In given model the black ball represent carbon atoms, white represent hydrogen atoms, blue represents nitrogen, yellow represent sulfur atom and red balls represent oxygen atoms.

a)

The amino acid that contains free amine group is labeled as N-terminal amino acid whereas, the amino acid that contains free carboxyl group is labeled as C-terminal amino acid.

b)

Observing the structure shows that it contains serine, cysteine, glutamine and alanine amino acids attached to each other.

The one letter abbreviation for serine, cysteine, glutamine and alanine is S,C,Q and A respectively. Therefore, the name of peptide by the use of one letter abbreviation is S-C-Q-A.