356589.fig.002a
(a) YGGFL
356589.fig.002b
(b) YGGFLK
356589.fig.002c
(c) YGGFLR
Figure 2: Mass spectra of the protonated oligopeptides YGGFL (a), YGGFLK (b), and YGGFLR (c) after GME-induced fragmentation. The peak at 136 in each of the spectra corresponds to the ion NH2+–CHR1(Y), where R1(Y) = CH2–C6H4–OH is the residue of the N-terminal tyrosine amino acid.