contains derives from (R)-5-oxo-1,4-tetrahydrothiazine-3-carboxylic acid S-carboxamidomethyl-L-cysteine deaminated residue cyclized N-terminal S-carboxamidomethyl-L-cysteine -17.026548385620117188 -17.030000686645507812 144.011932373046875 144.1699981689453125 C 5 H 6 N 1 O 2 S 1 S-carbamoylmethylcysteine cyclization (N-terminus) PSI-MOD (R)-5-oxoperhydro-1,4-thiazine-3-carboxylic acid A protein modification that effectively cyclizes an S-carboxamidomethyl-L-cysteine residue to (R)-5-oxo-1,4-tetrahydrothiazine-3-carboxylic acid with the loss of ammonia. MOD:01060 MOD:01871 5-oxothiomorpholine-3-carboxylic acid N-term Otc H -3 N -1 artifact Pyro-carbamidomethyl