Conform ational as pects of Glutathion e tripeptid e: electron density topological & natural bond orbital analyses

Glutathione (GSH ) is an un usual tripeptide (Ȗ-gluta myl–cystei nyl– glycine ) with a p eptide bond between the amine group of cysteine and the ca rboxylic group of the glutamic aci d side chain. GSH is on e of the mos t abundant ligands in living system s, with an almost ubiq uitous presen ce from bac teria to hum an cells. Th e interest in the study o f GSH is du e to the fact that,despite its structural simplicity, it exhibits a number of roles in detoxi¿cation of heavy metal ions, i n preventing oxidation stress dam ages and as a shuttle in transport o f metal ions and complexes. It can exist in its neutral form either as n eutral, zwitterionic, cationic and an ionic forms. The latter form predo minates in t he condensed phase. Th e lowest-energy zwitterionic struct ures of GS H have been calculated at the se mi-empirical AM۱ and PM۳ levels and comp ared to the e xperimenta l crystal stru cture. The modeling of the tripeptide underlin es the question of wheth er fundamental underst anding of p rotein conformation can be obtained on the le vel of substituent amino acids.

کلیدواژه ها:

Glut athione tripe ptide ، Ram achandran m ap ، Intramo lecular hydrogen bond ، AIM theory ، NBO analysis