SYNTHESIS AND GLUTATHIONE-S-TRANSFERASE STRUCTURE-AFFINITY RELATIONSHIPS OF NONPEPTIDE AND PEPTIDASE-STABLE GLUTATHIONE ANALOGS

A series of nonpeptidic glutathione analogues where the peptide bonds were replaced by simple carbon-carbon bonds or isosteric E double bond s were prepared. The optimal length for the two alkyl chains on either side of the mercaptomethyl group was evaluated using structure-affini ty relationships. Affinities of the analogues 14a-f, 23, and 25 were e valuated for a recombinant GST enzyme using a new affinity chromatogra phy method previously developed in our laboratory. Analysis of these a nalogues gives an additional understanding for GST affinity requiremen ts: (a) the carbon skeleton must conserve that of glutathione since an alogue 14a showed the best affinity (IC50 = 5.2 mu M); (b) the GST G s ite is not able to accommodate a chain length elongation of one methyl ene group (no affinity for analogues 14c,f); (c) a one-methylene group chain length reduction is tolerated, much more for the ''Glu side'' ( 14d, IC50 = 10.1 mu M) than for the ''Gly side'' (14b, IC50 = 1800 mu M); (d) the mercaptomethyl group must remain at position 5 as shown fr om the null affinity of the 6-mercaptomethyl analogue 14e; (e) the add itional, peptide isosteric E double bond (25) or hydroxyl derivative ( 23) in 14e did not help to retrieve affinity, This work reveals useful . information for the design of new selective nonpeptidic and peptidas e-stable glutathione analogues.