Flotation rates, molecular weights and hydrated densities of the low‐density lipoproteins

Abstract

A method involving three computer programs is described for characterizing the major component of the Sf 0–12 low‐density lipoprotein class by its Sf rate, hydrated density and molecular weight. All necessary information is obtained from a standard low and high‐density lipoprotein ultracentrifugal analysis. Moving‐boundary flotation rates are measured in 1.061 g/ml sodium chloride and 1.200 g/ml sodium bromide solutions and are corrected to flotation at zero concentration. Hydrated densities are calculated from η Fo versus ρ plots and minimum hydrated molecular weights calculated using Stokes' frictional factor, assuming spherical molecules. Preliminary application of this procedure indicates higher Sfo rates, higher molecular weights, and lower hydrated densities in females than in males. Molecular weights and standard deviations of the principal Sf 0–12 component for non‐fasting normal adult females and males were 2.36±0.16 and 2.12±0.20 millions, respectively.

Physicochemical properties of low-density lipoproteins of normal human plasma. Evidence for the occurrence of lipoprotein B in associated and free forms

“…When based on the same assumption and measured parameters, the molecular weights (2.38 x 106-2.58 x 106) of LD lipoprotein subfractions (LDL-IV, LDL-V and LDL-VI) of comparable hydrated densities were within the range reported in the literature. However, the inverse relationship between the hydrated density and molecular weight (Lindgren et al, 1969) within these three density ranges was not observed. Frictional ratios of LDL-V and LDL-VI subfractions clearly indicate that these lipoproteins were hydrated and/or deviated from a spherical shape.…”

“…Lindgren et al (1969) found a molecular weight of 2.12 x 106 for LD lipoprotein from men and 2.36 x 106 for women, whereas Adams & Schumaker (1969) found values of 2.1 x 106-2.6 x 106. When based on the same assumption and measured parameters, the molecular weights (2.38 x 106-2.58 x 106) of LD lipoprotein subfractions (LDL-IV, LDL-V and LDL-VI) of comparable hydrated densities were within the range reported in the literature.…”

“…Bjorklund & Katz (1956) established that the hydrated densities for the two LD subfractions with Sf 8.1 and Sf 6.4 were 1.0274 and 1.0328g/ml respectively. Lindgren et al (1969) reported hydrated densities of Sf 0-12 preparations to be 1.0304±0.0035g/ ml for men and 1.0284±0.0031g/ml for women. Molecular weights based on the hydrated density values of 1.034 or 1.030g/ml would be 10-30 % higher than that based on a hydrated density of 1.037g/ml.…”

“…Most ofthe reported studies (Lindgren et al, 1951(Lindgren et al, , 1969Adams & Schumaker, 1969) on the molecularweight determination of LD lipoprotein preparations were based on the assumption that these molecules are anhydrous spheres; the measured parameters were flotation coefficients and hydrated densities. Lindgren et al (1969) found a molecular weight of 2.12 x 106 for LD lipoprotein from men and 2.36 x 106 for women, whereas Adams & Schumaker (1969) found values of 2.1 x 106-2.6 x 106.…”

Associations of lecithin: cholesterol acyltransferase (LCAT) mass concentrations with exercise, weight loss, and plasma lipoprotein subfraction concentrations in men

“…Results are also described for the peak flotation rate (S f ) of the LDL-mass distribution [12,13]. Plasma lipoprotein cholesterol concentrations were measured directly by the methods of the Lipid Research Clinics [14], plasma apolipoprotein B concentrations were assessed by radioimmunoassay [15], apolipoprotein A-I and A-II concentrations were measured by radialimmunodiffusion [16], and LCAT mass was measured by double antibody radioimmunoassay [17].…”