2-mercaptopropionyl-gylcine (2-MPG) is one of the agents having a protective action against lipid peroxidation in vitro. Human low density lipoprotein (LDL) was easily denatured by an interaction with linoleic acid hydroperoxide or 85% of oxygen in our previous studies. The purpose of this study was to determine effects of 2-MPG on the formation process of denatured LDL which was due to interaction with linoleic acid hydroperoxide or 85% of oxygen. Human LDL was isolated from 6 healthy volunteers after an over-night fast. The isolated LDL was treated with 2-MPG, before an incubation with linoleic acid hydroperoxide or a saturation with 85% O2. Lipid staining pattern of the isolated LDL on polyacrylamide gel disc electrophoresis was modified by the interaction with linoleic acid hydroperoxide, and the incidence of modified LDL was dependent on time of the interaction and dose of the hydroperoxide at 37°C. The incidence was significantly reduced by the treatment with 2-MPG. Moreover, the effect of 2-MPG was dose-dependent. Lipid peroxide concentration in the isolated LDL was markedly increased under the condition saturated with 85% O2, whereas one in the pre-treated LDL with 2-MPG was not increased. The increase in LDL-lipid peroxide concentration was negatively correlated with the dose of 2-MPG. The results suggest that 2-MPG can prevent the formation of denatured human LDL. It is possible that the effect of 2-MPG is brought about by the inhibition of lipid peroxidation in lipoprotein particle.
