Isolation, purification, and characterization of glutathione S-transferase from oat (Avena sativa) seedlings

Glutathione S-transferase (GST) from oat seedlings was purified by ammonium sulfate precipitation and glutathione (GSH) affinity chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of two major protein subunits with molecular masses of 29 and 31 kDa, respectively. Isoelectric focusing revealed a major band with pi of 3.43 and a minor band with pi of 7.42. Kinetic analysis with respect to 1-chloro-2,4-dinitrobenzene (CDNB) as substrate revealed a K-m of 1.18 mM and V-max of 0.94 mu mol/min and a specific activity of 17.96 mu mol/min/mg. Inhibition studies indicated that oat GST is strongly inhibited by chlorophyllin, hemin, and anthocyanin and only weakly by bilirubin and biliverdin.