S-pyridylethyl-L-cysteine S-[2-(pyridin-2-yl)ethyl]-L-cysteine 105.0578460693359375 105.1399993896484375 2-PEC 2-vinylpyridine derivatized cysteine residue 208.0670318603515625 208.279998779296875 A protein modification that effectively converts an L-cysteine residue to S-[2-(pyridin-2-yl)ethyl]-L-cysteine. C C 10 H 12 N 2 O 1 S 1 C 7 H 7 N 1 From DeltaMass: (name misspelled "Pyridylethyl Cystenyl", and formula incorrect, N and O reversed) Formula: C10H12O2N1S1 Monoisotopic Mass Change: 208.067 Average Mass Change: 208.286 MOD:01438 PSI-MOD Pyridylethyl Pyridylethyl Cystenyl S-(pyridin-2-ylethyl)-L-cysteine S-pyridylethylation artifact