When an unknown peptide containing five amino acids is treated with an enzyme that hydrolyzes only the serine-leucine peptide bond, the fragments Leu-Cys, Ser, Leu-Ser are formed. What was the original amino acid sequence in the peptide?

Question

Quizplus · Accepted Answer

Since the enzyme only hydrolyzes the serine-leucine bond, the original peptide must have contained a serine-leucine bond that was cleaved to give the two fragments Leu-Ser and Ser. The remaining portion of the peptide must have contained a leucine-cysteine bond. The only option that fits this condition is D: Ser-Leu-Ser-Leu-Cys.

When an Unknown Peptide Containing Five Amino Acids Is Treated