sulfur substitution for oxygen modified glycine residue 1-thioglycine 1-thioglycine 15.977155685424804688 16.059999465942382812 2-amino-1-sulfanylethanone A protein modification that effectively converts a glycine residue to 1-thioglycine. C 0 H 0 N 0 O -1 S 1 Carboxy->Thiocarboxy G MOD:01625 MOD_RES 1-thioglycine PSI-MOD S(O)Gly This modification occurs naturally in two forms. At an interior peptide location (MOD:00270) it exists as aminoethanethionic acid, or aminoethanethioic O-acid. At the C-terminal (MOD:01623) it exists as aminoethanethiolic acid, or aminoethanethioic S-acid [JSG]. aminoethanethioic acid aminothioacetic acid natural thiocarboxylic acid