thioester crosslinked residues S-(L-tyrosyl)-L-cysteine -18.010564804077148438 -18.020000457763671875 265.064697265625 265.30999755859375 MOD:00827 C 12 H 13 N 2 O 3 S 1 H -2 O -1 Cross-link 2. natural C, Y tyrosine cysteine thioester C-term XLNK1TyrSCys A protein modification that effectively crosslinks an L-tyrosine residue and an L-cysteine residue by a thioester bond to form S-(L-tyrosyl)-L-cysteine. S-(L-tyrosyl)-L-cysteine CROSSLNK Tyrosyl cysteine thioester (Cys-Tyr) PSI-MOD S-[2-amino-3-(4-hydoxyphenyl)propanoyl]cysteine (2R)-2-amino-3-([(2S)-2-amino-3-(4-hydroxyphenyl)propanoyl]sulfanyl)propanoic acid crosslinked residues with loss of water crosslinked L-tyrosine residue