Enzymatic Assay of Phosphatidylcholine Hydroperoxide by Phospholipase A₂ and Glutathione Peroxidase-Based on Fluorometry with N-(9-Acridinyl)maleimide

Abstract

Phosphatidylcholine hydroperoxide was assayed with phospholipase A₂ and glutathione peroxidase, based on fluorometry with N-(9-acridinyl)maleimide. The hydroperoxide was poorly reduced by glutathione peroxidase, and was converted by phospholipase A₂ into reactable forms of glutathione peroxidase. A linear relationship was found between hydroperoxides assayed by the enzymatic and chemical methods in the range from 0. 05 to 5. 0 nmol with 0. 5 to 1. 5 mg of the sample. The hydroperoxides of fatty acids, triacylglycerol and phosphatidylcholine were assayed in their mixtures and in commercial lecithins.