Which is the structure of the pentapeptide that gave lys-leu-phe on reaction with cyanogen bromide, and gave fragments met-lys, leu-phe, and arg on reaction with trypsin.

Question

Quizplus · Accepted Answer

The presence of lys-leu-phe indicates that there is a peptide bond between these three amino acids. Reaction with cyanogen bromide cleaves the peptide bond between lys and leu, resulting in a dipeptide consisting of lysine and leucine, and a tripeptide consisting of phenylalanine and the C-terminal end of the original peptide. Reaction with trypsin indicates that there is an arginine residue in the peptide that is cleaved by trypsin, giving a dipeptide of methionine and lysine and a tripeptide of leucine and phenylalanine. Putting these pieces together, we can see that the original pentapeptide must be arg-met-lys-leu-phe.

Which Is the Structure of the Pentapeptide That Gave Lys-Leu-Phe