A peptide was analyzed with the following results. What is the primary sequence of the peptide? To receive full (or partial) credit, briefly state the conclusions of each experimental result and indicate your logic.
a) Mass spectrometry was consistent with a peptide of 7 amino acids containing W, C,D, M,N, K, and I.
b) One cycle of Edman degradation of the peptide yielded a single product, the PTH derivative of I
c) Cleavage of the peptide with CNBr yielded two products. One contained 5 amino acids, and the other 2. One cycle of Edman degradation yielded the PTH derivatives of I and N, respectively.
d) Treatment of the peptide with trypsin yielded 2 products. One of them had significant light absorbance at 280 nm, and Edman degradation yielded the PTH derivative of I. The other trypsingenerated product contained 4 amino acids, and Edman degradation yielded the PTH derivative of Asp.