The two majors subspecies of high density lipoproteins (HDL), HDL3, were obtained from the plasma of normolipidemic male and female human subjects by a single zonal ultracentrifugation step. These two species were evaluated for homogeneity by compositional, physical, and quantitative immunochemical criteria. Three subfractions of HDL2 and five subfractions of HDL3 were obtained by recentrifugation and analyzed. In the analytical ultracentrifuge, the three HDL2 subfractions exhibited flotation rates (S0(f)1.21) of 6.1, 5.9, and 4.8; the five HDL3 subfractions showed S0(f)1.21 of 3.3, 2.9, 2.8, 1.9, and 1.7 S0(f)1.21 varied directly with lipid content and particle weight and inversely with zonal rotor effluent volume and hydrated density. Apoprotein composition differed also among the subfractions. In the order of decreasing S0(f)1.21, the apo-A-I/apo-A-II molar ratios were 18.5, 11.1, 7.6, 2.1, 2.0, 2.4, 3.0, and 2.9, respectively. In normolipidemic plasma from either sex, the S0(f)1.21=5.9 fraction of HDL2 and the S0(f)1.21=2.9 fraction of HDL3 were the most abundant. The data indicate that HDL in man contain density subclasses whose relative plasma concentrations can vary: a rather homogenous HDL2 with an average density of 1.096 g/ml, and a heterogenous HDL3 consisting primarly of particles with an average density of 1.140 g/ml, and in lesser abundance, particles with an average density of 1.160 g/ml. Both of these populations are flanked by closely related particles in lower amounts, suggesting the existence of two distinct subclasses. The data, however, do not rule out that these subclasses are the most prominent representatives of a continuum of gradually differing particles composing HDL3.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Biological Chemistry|
|State||Published - 1980|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology