S-(L-isoglutamyl)-L-cysteine -17.026548385620117188 -17.030000686645507812 214.0412139892578125 214.2400054931640625 XLNK-SCys-5Glu(Gln) Cross-link 2; DeltaMass calculates the mass difference from glutamic acid rather than glutamine. A protein modification that effectively crosslinks an L-cysteine residue and an L-glutamine residue by a thioester bond with the formation of S-(L-isoglutamyl)-L-cysteine and the release of ammonia. (S,R)-2-amino-4-[S-(2-amino-2-carboxyethyl)thiocarboxy]butanoic acid PSI-MOD none gamma-(S-cysteinyl)glutamic acid S-(L-isoglutamyl)-L-cysteine H -3 N -1 C 8 H 10 N 2 O 3 S 1 natural CROSSLNK Isoglutamyl cysteine thioester (Cys-Gln) MOD:00117 S-gamma-glutamyl (crosslinked to cysteine) (2S)-2-amino-5-[(2R)-2-amino-2-carboxyethyl]sulfanyl-5-oxopentanoic acid C, Q 2-amino-5-(2-amino-2-carboxyethyl)thio-5-oxopentanoic acid thioester crosslinked residues crosslinked residues with loss of ammonia crosslinked L-glutamine residue