Nonenzymatic glycosylation of proteins. II. Does glycosylation of low density lipoproteins affect lipid composition of erythrocyte membranes?

The degree of nonenzymatic glycosylation of low density lipoprotein (LDL) and lipid composition of LDL as well as of erythrocyte membrane ghosts was investigated in order to determine the possible relationship of LDL glycosylation and lipid metabolism disorders. Three groups of juveniles attending outpatient clinic: diabetics without associated conditions, diabetics with background retinopathy and control healthy subjects were selected for our study. Anisotropy measurements and chemical determinations revealed that enhanced LDL glycation in diabetics (20.6 +/- 1.5 in uncomplicated diabetic subjects and 21.4 +/- 1.0 in retinopathic patients versus 18.1 +/- 1.9 controls) corroborated significantly with membrane cholesterol: phospholipid ratio (r = 0.695), LDL cholesterol (r = 0.720) and membrane rigidization (r = 0.504). Moreover, the elevation of LDL glycation, significance of which was established by nonparametric variance analysis (p less than 0.01), was considerably correlated with total plasma cholesterol (r = 0.743). The possibility that chemical modification of LDL by glucose might induce the altered cholesterol metabolism and distribution was suggested.