A compound of formula (1) and the alkyl-type (1-10C), alkenyl-type (1-10C), and arylalkyl-type (7-12C) esters, amides and mixed ester/amides thereof; wherein Z is selected from the group consisting of S, O, and C; n is 1, 2 or 3; wherein when Z is O or S and n is 1, X is a mono- or disubstituted or unsubstituted hydrocarbyl (1-20C) moiety optionally containing 1 or 2 nonadjacent heteroatoms (O, S or N), and wherein said substitution is selected from the group consisting of halo, -NO, -NO2, -NR2, OR, and SR, wherein each R is independently H or lower alkyl (1-4C); wherein when Z is S and n is 2, one X is as above defined and the other X is lower alkyl (1-4C); and wherein when Z is C and n is 3, one X is as above defined and the other two X are independently H or lower alkyl (1-4C); Y-CO is selected from the group consisting of η-Glu, β-Asp, Glu, Asp, ηGlu-Gly, β-Asp-Gly, Glu-Gly, and Asp-Gly, and AAC is an amino acid coupled through a peptide bond to the remainder of the compound of formula (1), are useful as affinity ligands, elution reagents, solution inhibitors, diagnostic reagents and therapeutics. These compounds and analogous tripeptide glutathione analogs can be used as members of panels to obtain specific characteristic profiles for various glutathione-S-transferases.