L-proline thiazole-4-carboxylic acid -20.026214599609375 -20.030000686645507812 180.035736083984375 180.2299957275390625 none CROSSLNK Thiazole-4-carboxylic acid (Pro-Cys) H -4 O -1 L-proline thiazole-4-carboxylic acid natural C, P Cross-link 2. A protein modification that effectively crosslinks an L-cysteine residue and an L-proline residue to form L-proline thiazole-4-carboxylic acid. C 8 H 8 N 2 O 1 S 1 2-[(2S)-pyrrolidin-2-yl]-1,3-thiazole-4-carboxylic acid MOD:01405 PSI-MOD thiazole/thiazoline ring crosslinked residues crosslinked L-proline residue didehydrogenated and dehydrated residue