modified L-tryptophan residue 2',3'-dihydrotryptophan 188.0949554443359375 188.2299957275390625 2.0156500339508056641 2.0199999809265136719 A protein modification that by reducing the indole ring system of tryptophan to indoline effectively converts an L-tryptophan residue to 2',3'-dihydrotryptophan. W H 2 MOD:00962 C 11 H 12 N 2 O 1 none PSI-MOD artifact From DeltaMass: References:1. Pearson,D.A., Blanchette,M., Baker,M.L. and Guindon,C.A. (1989) Trialkylsilanes as scavengers for the trifluoroacetic acid deblocking ofprotecting groups in peptide synthesis. Tetrahedron Lett., 30(21), 2739-2742 Notes: Reduction of indole double bond of Trp which occurs when triethylsilane (TES) is used as a scavenger and Trp is incorporated without protection of indole nitrogen [1]. This side reaction is likely to be accompanied by oxidation of indoline ring with formation of intensively colored peptide by-products. Triisopropylsilane (TIPS) does not give this side reaction. See structure at http://www.abrf.org/images/misc/dmass2.gif. [However, the pictured indoline structure is incorrect - JSG]. hydrogenated residue