The stability of glutathione peroxidase activity in plasma from cattle, pigs and sheep on storage in the presence and absence of glutathione

Abstract

Ovine, bovine and porcine plasma glutathione peroxidase (GSH-Px) activity decreased on storage at both 4 degrees C and 20 degrees C. The ovine and bovine enzymes were significantly less stable than the porcine enzyme. The addition of GSH to a final concentration of 2 mmol/L to plasma samples at the commencement of storage retarded the loss of both ovine and bovine plasma GSH-Px activity. The ovine enzyme was unique in that after inactivation by storage at 4 degrees C, incubation with GSH restored the enzyme activity. It is recommended that plasma GSH-Px should be assayed fresh, or otherwise stored at -20 degrees C.