Table 1. Peptides identified in bacteria with LC-MS/MS.

bacteria	substrate	number of peptides	number of trp peptides	number of 1-L-MT peptides
S. aureus	L-tryptophan	390	8	0
S. aureus	1-L-MT	45	11	0
S. agalactiae	L-tryptophan	247	7	0
S. agalactiae	1-L-MT	300	12	0

Total numbers and numbers of tryptophan (trp) containing peptides are given for protein samples from different bacteria grown either with L-tryptophan or 1-L-MT as unique available tryptophan source. For all analyses, tryptophan methylation was used as a variable modification, but none of the peptides identified contained methylated tryptophan.