Flotation equilibrium of serum low density lipoproteins

Nelson, Charles A.; Lee, J.A.; Brewster, Marge A.; Morris, Manford D.

doi:10.1016/0003-2697(74)90010-4

Cited by 33 publications

(12 citation statements)

References 10 publications

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“…In cases where there is a preferential solvation with one of the components, a marked curvature of these plots would result (see, for example, Aune and Timasheff, 1970). In the case of low-density lipoproteins, a system more analogous to ours, Nelson et al (1974) found good agreement between the molecular weights derived by varying p with KBr in equilibrium studies and those obtained by other methods and also that the molecular weight was not affected by changes in salt concentration.…”

Section: Resultssupporting

confidence: 83%

“…Thus, a plot of p against s will produce a straight line having an intercept of 1 /v and a slope of (-RT)/(DMu). This is essentially the same treatment for velocity data as that used for sedimentation equilibrium data by Nelson et al (1974) for determining both v and M of serum lipoprotein by using solvents of different densities. Solid KBr was added to samples of complex to adjust the density to the range 1.2-1.34 g/cm3.…”

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confidence: 99%

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Size and shape of the model lipoprotein complex formed between glucagon and dimyristoylglycerophosphocholine

Aj¹,

Epand²,

Lin³

et al. 1978

Biochemistry

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Glucagon forms water-soluble lipoprotein particles with dimyristoylglycerophosphocholine at temperatures below the phase-transition temperature of the lipid. The shape and size of this lipoprotein particle were studied by viscometry, sedimentation velocity, sedimentation equilibrium, quasielastic light scattering, and electron microscopy using both negative-staining and freeze-fracture techniques. The lipoprotein particle has an oblate ellipsoid shape with dimensions of 250 X 70 A and an approximate molecular weight of 1.4 X 106. This molecular weight is similar to that found for small unilamellar phospholipid vesicles but is achieved in the presence of glucagon without sonication. The shape of the glucagon lipoprotein particle is similar to that found for the complex formed between some serum apolipoproteins and dimyristoylglycerophosphocholine. From these data, a model for the glucagon-dimyristoylglycerophosphocholine is proposed consisting of a single bilayer of phospholipid with the glucagon incorporated into the bilayer structure in such a manner as not greatly to disturb the average area occupied per phospholipid molecule.

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Section: Resultssupporting

confidence: 83%

mentioning

confidence: 99%

Size and shape of the model lipoprotein complex formed between glucagon and dimyristoylglycerophosphocholine

Aj¹,

Epand²,

Lin³

et al. 1978

Biochemistry

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“…Hydrodynamic Studies-Flotation equilibrium experiments were carried out at 20°C in a Beckman XLI analytical ultracentrifuge using interference optics following procedures described by Nelson et al (27) to experimentally determine both the partial specific volume (v ) and the apparent weight average molecular weight (M r(app) ). Three aliquots of apoE3-(126 -183)⅐DMPG complexes were dialyzed against three buffer solutions containing 100 mM Tris (pH 7.2) and different concentrations of KBr or NaBr, providing solvent densities of 1.25, 1.30, and 1.35 g/ml and protein concentrations of 0.50, 0.59, and 0.31 mg/ml, respectively.…”

Section: Methodsmentioning

confidence: 99%

Structural Characterization of a Low Density Lipoprotein Receptor-active Apolipoprotein E Peptide, ApoE3-(126–183)

Raussens¹,

Mah²,

Kay³

et al. 2000

Journal of Biological Chemistry

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Apolipoprotein E (apoE) plays a critical role in lipoprotein particle clearance from blood plasma through its interaction with the low density lipoprotein (LDL) receptor and other related receptors. Here, we studied a 58-residue peptide encompassing the receptor binding region of apoE. ApoE3-(126 -183) was generated by cyanogen bromide cleavage of recombinant apoE3-(1-183), purified by reversed-phase high pressure liquid chromatography, and characterized by mass spectrometry.

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“…Analytical Ultracentrifugation. A Beckman Model E analytical ultracentrifuge using the Rayleigh interference optical system was used for flotation equilibrium experiments, which were performed as described by Nelson et al (1974).…”

Section: Methodsmentioning

confidence: 99%

Factors Affecting the Stability and Conformation of Locusta migratoria Apolipophorin III

Pm¹,

Cm²,

Oikawa³

et al. 1994

Biochemistry

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Apolipophorin III (apoLp-III) from the migratory locust, Locusta migratoria, represents the only full-length apolipoprotein whose three-dimensional structure has been solved. In the present study, spectroscopic methods have been employed to investigate the effects of deglycosylation (via endoglycosidase F treatment) and complexation with lipid on the stability and conformation of this protein. Addition of isolated lipid-free apoLp-III to sonicated vesicles of dimyristoylphosphatidylcholine (DMPC) resulted in the formation of relatively uniform disklike complexes with an average Strokes diameter of 13.5 nm. Flotation equilibrium experiments conducted in the analytical ultracentrifuge revealed a particle molecular mass of 588 500 Da. Chemical cross-linking and compositional analysis of apoLp-III.DMPC complexes indicated five apoLp-III molecules per disk and an overall DMPC:apoLp-III molar ratio of 122:1. Circular dichroism (CD) spectra of apoLp-III samples suggested a loss of alpha-helical structure upon deglycosylation, while complexation with DMPC did not significantly alter the helix content (estimated to be > 75%). Fluorescence spectroscopy revealed that the apoLp-III tryptophan fluorescence emission maximum was blue-shifted from 347 to 332 and 321 nm upon deglycosylation and complexation with DMPC, respectively. In quenching experiments with native apoLp-III, tryptophan residues were shielded from the positively charged quencher, CsCl. Increased exposure to KI, CsCl, and acrylamide was observed upon deglycosylation, whereas complexation with DMPC yielded lower Ksv values for KI and acrylamide and an increased value for CsCl versus native lipid-free apoLp-III. In guanidine hydrochloride denaturation studies monitored by CD or fluorescence, native, lipid-free apoLp-III displayed a denaturation midpoint of 0.60 M, and delta GDH2O = 5.37 kcal/mol was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

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Flotation equilibrium of serum low density lipoproteins

Cited by 33 publications

References 10 publications

Size and shape of the model lipoprotein complex formed between glucagon and dimyristoylglycerophosphocholine

Size and shape of the model lipoprotein complex formed between glucagon and dimyristoylglycerophosphocholine

Structural Characterization of a Low Density Lipoprotein Receptor-active Apolipoprotein E Peptide, ApoE3-(126–183)

Factors Affecting the Stability and Conformation of Locusta migratoria Apolipophorin III

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