crosslinked residues with loss of water alaninohistidine (serine crosslinked to tele or pros nitrogen of histidine) -18.010564804077148438 -18.020000457763671875 206.08038330078125 206.1999969482421875 A protein modification that effectively crosslinks an L-serine residue and an L-histidine residue to release water and form tele- or pros-(2-amino-2-carboxyethyl)histidine. C 0 H -2 N 0 O -1 C 9 H 10 N 4 O 2 Cross-link 2; From DeltaMass with no citation or formula: Average Mass: -18. The DeltaMass description "Serine crosslinked to theta or pi carbon of Histidine" is incorrect. The histidine ring nitrogens (not carbons) are designated tele or N-tau (not theta), and pros or N-pi [JSG]. H, S MOD:00955 PSI-MOD artifact beta-alaninohistidine crosslinked L-histidine residue crosslinked L-serine residue