The oxidized form of glutathione

The crystal structure of the oxidized form of the tripeptide glutathione (g amma-L-glutamyl-L-cystylglycine octahydrate, C20H32N6O12S2. 8H(2)O) has bee n determined at 100 K. The molecule was crystallized from aqueous solution in the presence of the precipitating agent polyethylene glycol by the vapor -diffusion method, which is commonly used in protein crystallization. The s pace group is P2(1)2(1)2 and the molecule contains a crystallographic twofo ld symmetry axis through the middle of the disulfide bridge. There are four water molecules per tripeptidc, two of which are disordered. The S-S and S -C bond lengths are 2.0387(9) and 1.8098(19) Angstrom, respectively and the C-S-S bond andle is 105.03(6)degrees.