FIGURE 3.
A: Schematic diagram of chymotrypsinogen precursor and chymotrypsin chains. Cleavage sites for neo-chymotrypsinogen activation pathway shown with arrows, with excised dipeptides as dots; adapted from reference 19. Peptides seen in spots 16–20 shown in black, peptide identified in spots 17 and 18 with crosshatching. See text for details. B: MALDI-PSD fragmentation spectra of peptide present only in spots 17 and 18, with parent ion mass m/z 1561. The peptide consists of residues 19–88, containing the A chain plus the dipeptide linker between the A and B chains. Immonium, di-, tripeptide, b, and y ions are labeled for the sequence CGVPAIHPVLSGLSR, assuming the cysteine is carbamidomethylated.