Synthetic analogs for oxovanadium(IV/V)-glutathione interaction: an NMR, EPR, synthetic and structural study of oxovanadium(IV/V) compounds with sulfhydryl-containing pseudopeptides and dipeptides

The reaction of [VO(CH3COO)(2)(phen)] (phen=1,10-phenanthroline) with the s ulfhydryl-containing pseudopeptides (scp), N-(2-mercaptopropionyl) glycine (H(3)mpg), N-(2-mercaptopropionyl) cysteine (H(4)m(2)pc), N-(3-mercaptoprop ionyl)cysteine (H(4)m(3)pc) and the dipeptides glycylglycine (H(2)glygly) a nd glycyl-L-alanine (H(2)glyala), in the presence of triethylamine, results in the formation of the compounds Et3NH[VO(mpg)(phen)] (1), (Et3NH)(2)[VO( m(2)pc)] (4), [Et3NH)(2)[VO(m(3)pc)] (5), [VO(glygly)(phen)] . 2CH(3)OH (2 . 2CH(3)OH) and [VO(glyala)(phen)] . CH3OH (3 . CH3OH). Evidence for the mo lecular connectivity in 2 . CH3OH was established by X-ray crystallography, showing the vanadium(IV) atom ligated to a tridentate glygly(2-) ligand at the N-amine, N-peptide and O-carboxylato atoms. Combination of the correla tion plot of the EPR parameters g(z) versus A(z), together with the additiv ity relationship supported the prediction of the equatorial donor atom sets of the (VO2+)-O-IV center at various pH values for the (VO2+)-O-IV-glutath ione system considered in this study. Model NMR studies (interaction of van adium(V) with the sep H(3)mpg) showed that there is a possibility of vanadi um(V) ligation to glutathione. (C) 2000 Elsevier Science Inc. All rights re served.