IDENTIFICATION OF OXIDIZED LOW-DENSITY-LIPOPROTEIN IN HUMAN SERUM BY NMR-SPECTROSCOPY

1. In this study we compared the 500 MHz H-1-NMRs from native and oxid ized low-density lipoproteins. 2. The measurements revealed a characte ristic pattern of three resonances in spectra from oxidized, but not f rom native low-density liprotein at 1.17 p.p.m., 1.18 p.p.m. and 1.20 p.p.m. (relative to 3-trimethylsilyl-[2,2,3,3-H-2(4)]-propionate). 3. A quantitative comparison between these resonances in sera from patien ts with coronary heart disease and healthy control subjects revealed t hat the intensity was significantly higher in patients with coronary h eart disease (1.17 p.p.m.: 0.026 +/- 0.014 versus 0.015 +/- 0.019; 1.1 8 p.p.m.: 0.032 +/- 0.011 versus 0.017 +/- 0.021; 1.20 p.p.m.: 0.030 /- 0.066 versus 0.010 +/- 0.005; P < 0.05 compared with healthy contro l subjects for each resonance). 4. Fractionation of sera from patients with coronary heart disease revealed that the resonances equal to tho se obtained from experimentally oxidized low-density lipoprotein are i ndeed caused by the low-density lipoprotein fraction of the sera. 5. W hen the NMRs from sera were calibrated with oxidized low-density lipop rotein prepared by Cu2+ oxidation, a concentration of 66.5 +/- 28.6 mu g/ml and 36.3 +/- 23.7 mu g/ml (P < 0.05) was estimated in patients w ith coronary heart disease and healthy subjects respectively. Elevated levels of oxidized low-density lipoprotein also occurred in those pat ients with normal serum concentrations of total low-density lipoprotei n. 6. The study shows a simple method to measure oxidized low-density lipoprotein in human serum and may gain interest to assess the cardiov ascular risk factor profiles more completely.