modified L-tryptophan residue 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid 12.0 12.010000228881835938 198.079315185546875 198.220001220703125 C 12 H 10 N 2 O 1 A protein modification that effectively converts an N-terminal L-tryptophan residue by a formadehyde adduct to 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid. W C 1 MOD:00966 From DeltaMass: Average Mass: 12 Average Mass Change: 12 References: Lippke, K. P., W. G. Schunack, W. Wenning, W. E. Mueller. 1983..beta.-Carbolines as benzodiazepine receptor ligands. 1. Synthesis andbenzodiazepine receptor interaction of esters of.beta.-carboline-3-carboxylic acid. J. Med. Chem.26: 499-503 Cain, M., R. W. Weber, F. Guzman, J. M. Cook, S. A. Barker, K. C.Rice, J. N. Crawley, S. M. Paul, P. Skolnick. 1982. .beta.-Carbolines:synthesis and neurochemical and pharmacological actions on brainbenzodiazepine receptors.J. Med. Chem. 25: 1081-91 Notes: +12 Da modification corresponds to formaldehyde adduct of Trp having beta-carboline structure (methylene bridge links carbon-2 of indole ring and alfa-N. See structure at http://www.abrf.org/images/misc/dmass12a.gif; modification in red. artifact PSI-MOD none