Figure 7. MS/MS spectra for a tryptophan-containing peptide from 86HG39 cell culture lysate.

86HG39 cells were grown in the presence of L-tryptophan (A) or 1-L-MT (B). From the spectra shown, the peptide SADTLWDIQK from human L-lactate dehydrogenase B chain was identified with a mascot score of 54 in both samples. For cells grown in the presence of L-tryptophan or 1-L-MT, the spectra appear almost identical. Fragment ions identifying the tryptophan residue are clearly visible and are marked with an asterisk.