Glutathione S-transferase (EC 2.5.1 .18) is present in wheat flour (0·07 mg enzyme/g flour). It was purified by hydrophobic interaction chromatography on phenyl Sepharose CL-4B and affinity chromatography on S-hexylglutathione Sepharose 6B. The enzyme is a homodimer with subunit molecular weight of 27500 and an isoelectric point of 5·9. It conjugated glutathione (Km = 0·37 mm) with 1-chloro2,4-dinitrobenzene with a specific activity of 30μmol/min/mg protein. Linoleic acid hydroperoxides were reduced, with a specific activity of 60 nmol/min/mg protein for the 9-hydroperoxy-trans- 10,cis-l2-octadecadienoic acid isomer. The possible contribution of glutathione S-transferase to the baking properties of wheat is discussed.
- 13-hydroperoxy-cis-9,trans-1 1-octadecadienoic acid
- 9-hydroperoxy-trans- 10,cis-12-octadecadienoic acid
- oxidised glutathione
- polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate
- reduced glutathione