Reaction of the peptide, ala-met-lys-ser, with phenylisothiocyanate (PITC) at pH 8.0 followed by mild acidification (first cycle of Edman method) would release:
A) the labeled peptide ala-met-lys-ser-PTH.
B) PTH-ala, PTH-ser, PTH-lys and PTH-met.
C) PTH-ser and the peptide ala-met-lys.
D) PTH-ala and the peptide met-lys-ser.
E) All of the above.

Question

Quizplus · Accepted Answer

The Edman degradation method sequentially removes one residue at a time from the N-terminus of a peptide. In this case, alanine (ala) is at the N-terminus, so the reaction with phenylisothiocyanate (PITC) followed by acidification would release PTH-ala and leave the peptide met-lys-ser.

Reaction of the Peptide, Ala-Met-Lys-Ser, with Phenylisothiocyanate (PITC) at PH