Differences in carbohydrate content of low density lipoproteins associated with low density lipoprotein subclass patterns.

The neutral carbohydrate content of both the protein (apoB) and lipid fractions of low density lipoproteins (LDL) from subjects with a predominance of small, dense LDL (subclass pattern B) was found to be lower than in subjects with larger LDL (subclass pattern A): 45 +/- 12 versus 64 +/- 13 mg/g apoLDL, and 58 +/- 8 versus 71 +/- 8 mg/g apoLDL (P less than 0.0005 for both). Sialic acid content of LDL lipids, but not apoB, was also reduced in subclass pattern B. ApoB and glycolipid carbohydrate content of total LDL and LDL density subfractions declined with increasing LDL density and decreasing particle diameter. Moreover, in LDL subfractions from pattern B subjects, carbohydrate content of LDL apoB, but not LDL glycolipid, was significantly lower in comparison with particles of similar size from pattern A subjects. Thus, in LDL subclass pattern B, reductions in LDL carbohydrate content are associated both with reduced concentrations of larger carbohydrate-enriched LDL subclasses, and with reduced glycosylation of apoB in all LDL particles. LDL glycolipids may vary with overall lipid content of LDL particles, but variation in apoB glycosylation may indicate differences in pathways for LDL production, and reduced apoB glycosylation may reflect the altered metabolic state responsible for LDL subclass pattern B.