. Author manuscript; available in PMC: 2012 Feb 18.

Published in final edited form as: Chem Res Toxicol. 2011 Jan 7;24(2):204–216. doi: 10.1021/tx100275t

Table 5.

Modifications Observed in “Rat Liver” Data set.

mass	residues	modification name^a	peptides	spectra
40	G at 2nd position	Acetone	482	1862
−17	Q	Pyro-glutamic acid	85	301
42	N-terminus	Acetylation	65	286
22	D, E, T, S	Sodium adduct	110	260
26	N-terminus, S, T	Acetaldehyde	37	252
28	D, K, S, T, N-terminus	Dimethylation or formylation	118	248
−18	D, E, S, T	Dehydration	22	214
134	C	Unexpected	23	117
1	N, Q	Deamidation	40	78
38	D, E	Potassium adduct	31	63
16	W	Oxidation	5	43
25	C	Unexpected	10	37
−2	C	Intra peptide C-C disulphide bridge	15	24
14	V	Subsititution Ile/Leu for Val	7	24
14	R, D	Methylation	3	21
60	S	Unexpected	2	21
40	C	Pyro-carbamidomethyl	9	20
30	R	Subsititution of Trp for Arg*	1	17
105	C	SelenoCys+Carbamidomethyl*	1	10
−17	N	N-succinimide	4	6

^(a)

UniMod annotation corresponding to the most frequently observed modification mass. Alternative modification names were included for ambiguous mass shifts. Asterisk denotes single peptide modifications with strong spectral evidence (Supplemental File 10).