Jan 1, 1978

Properties and physiological function of a glutathione reductase purified from spinach leaves by affinity chromatography

Planta
B Halliwell, C Foyer

Abstract

Glutathione reductase (EC 1.6.4.2) was purified from spinach (Spinacia oleracea L.) leaves by affinity chromatography on ADP-Sepharose. The purified enzyme has a specific activity of 246 enzyme units/mg protein and is homogeneous by the criterion of polyacrylamide gel electrophoresis on native and SDS-gels. The enzyme has a molecular weight of 145,000 and consists of two subunits of similar size. The pH optimum of spinach glutathione reductase is 8.5-9.0, which is related to the function it performs in the chloroplast stroma. It is specific for oxidised glutathione (GSSG) but shows a low activity with NADH as electron donor. The pH optimum for NADH-dependent GSSG reduction is lower than that for NADPH-dependent reduction. The enzyme has a low affinity for reduced glutathione (GSH) and for NADP(+), but GSH-dependent NADP(+) reduction is stimulated by addition of dithiothreitol. Spinach glutathione reductase is inhibited on incubation with reagents that react with thiol groups, or with heavymetal ions such as Zn(2+). GSSG protects the enzyme against inhibition but NADPH does not. Pre-incubation of the enzyme with NADPH decreases its activity, so kinetic studies were performed in which the reaction was initiated by adding NADPH or...Continue Reading

  • References22
  • Citations78

References

  • References22
  • Citations78

Citations

Mentioned in this Paper

Spinach preparation
Hydrogen Peroxide
Glucose-6-phosphate Dehydrogenase Activity
Fructose
Chloroplast Stroma
Enzymes, antithrombotic
Glutathione Disulfide
Spinacia oleracea
GAPDH gene
Dithiothreitol

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