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            C Nuclear Magnetic Resonance Spectroscopy of Native and Recombined Lipoproteins

Assmann, Gerd; Highet, R. J.; Sokoloski, Edward A.; Brewer, H. B.

doi:10.1073/pnas.71.9.3701

Cited by 38 publications

(11 citation statements)

References 21 publications

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“…Its location in the bilayer has been of particular interest, and suggestions have been made that the polar hydroxyl moiety on the cholesterol interacts with possibly the N-methyl region, or the phosphate region, or the carbonyl region where the fatty acid chains are esterified to the glycerol. Cholesterol does not affect the T1 relaxation times of the N-methyl headgroup protons or carbon atoms (26,27). These results suggest that the effect of the cholesterol OH group on trimethylammonium group motion is negligible.…”

Section: Discussionsupporting

confidence: 53%

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study.

Yèagle¹,

Hutton²,

Huang³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

157

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The nuclear Overhauser effect has been observed in the nuclear magnetic resonance spectra of 31p. The information content of the nuclear Overhauser effect has been applied to the structure and dynamic properties of phosphatidylchoiine vesicles. In the vesicles only % of the theoretical maximum nuclear Overhauser effect enhancement is observed. This result is accounted for by dipolar interactions between the N-methyl protons and the phosphate of phosphatidylcholine, and a correlation time for internal motion of 1.4 X 10-9 sec. Addition of up to 30% cholesterol does not change the nuclear Overhauser effect enhancement or spin-lattice relaxation time of the vesicles. It is argued that the OH group of cholesterol is hydrogen bonded to the ester carbonyl oxygen of the phosphatidylcholine molecules. Amphiphilic molecules such as phospholipids and sterols are major lipid constituents of many membranes of mammalian cells and subcellular organelles. In recent years the molecular interactions of phospholipids and steroids in the lamellar gel and liquid-crystalline phases have been studied in detail by a variety of physical techniques (1-5). Although the effects of cholesterol on the structural and motional properties of phospholipid bilayers are becoming better understood (6, 7), the emphasis of previous investigations has been placed primarily on the hydrocarbon region of the bilayer system. Information on the importance of the interactions between phospholipids and steroids, especially the involvement of 30-OH group of cholesterol, in the polar head region is accumulating (8, 9), but little is known about either the precise position of the hydrophilic hydroxyl group of cholesterol in the bilayer, or which of the groups, such as the phosphate, quaternary ammonium, and carbonyl groups of phosphatidylcholine, is participating in the phospholipid-cholesterol interaction in the polar head region of the bilayer system. In order to investigate the interactions involving the polar groups of phosphatidylcholine with cholesterol, we have used phosphorus nuclear magnetic resonance (31P NMR).In this communication, we report evidence for a choline N-methyl proton interaction with the phosphate group of phosphatidylcholine in a vesicle bilayer system. The results suggest an intermolecular association which provides a model for the surface of the bilayer, and for molecular motion in the headgroup. The effects of added cholesterol lead to the conclusion that cholesterol does not interact with the phosphate group and that high percentages of cholesterol change the conformation of the headgroup, or, alternatively, the motion of that region. EXPERIMENTAL MATERIALS AND PROCEDURESEgg phosphatidylcholine (PC) was isolated and purified as described (10). PC in which the N-methyl groups were fully deuterated was prepared by Dr. Barry Lentz with phosphatidic acid hydrolyzed from egg PC by action of phospholipase D, and subsequently condensed with deuterated choline acetate (11). The lipid was purified by silicic acid chromatography. Cho...

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Section: Discussionsupporting

confidence: 53%

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study.

Yèagle¹,

Hutton²,

Huang³

et al. 1975

Proc. Natl. Acad. Sci. U.S.A.

157

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“…3, 5, 8, 9, 10, and 12: Reassembled lipoproteins isolated as infranatant fraction (3 ml) after ultracentrifugation at density 1.063 g/ml. HDL(2) *: native HDL labeled in its cholesterol ester moiety using 1,2-[dioleoyl-1-_4C]-sn-phosphatidylcholine as substrate for lecithin-cholesterol-acyltransferase (24).…”

Section: Resultsmentioning

confidence: 99%

Lipid-Protein Interactions in High Density Lipoproteins

Assmann

Brewer

1974

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

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Delipidated high density lipoprotein (apo-HDL), isolated apolipoproteins apoA-I and apoA-II, Scarboxymethylated apoA-II, apoC-I1, the NH2-and CO-OH-terminal CNBr peptides of apoA-II, and the COOH_ terminal CNBr peptide of apoA-I were recombined in vitro with [N-C3H3-cholinelphosphatidylcholine (PC) and (SPM). The It has been shown (1-4) that the protein moiety of human serum high density lipoprotein (HDL), prepared in its lipidfree form (apoHDL) by treatment with organic solvents (5, 6) retains its capacity to bind lipids, both in vivo (7) and in vitro (3,8). About 90% of the protein moiety of apoHDL is composed of two major apoproteins, designated as apoA-I and apoA-II, or, by their COOH-terminal amino acids, as apoGln-I and apoGln-JI (9-16); the remaining 10% is mainly composed of three minor apoproteins (apoC-I, apoC-II, and apoC-III), also associated with the very low density lipolprotein family (9). The complete amino-acid sequences of apoA-II, apoC-I, and apoC-III have been reported (17)(18)(19) 1.063 and 1.210 g/ml, and delipidated with chloroformmethanol, 2:1 (6). The procedures used in the isolation and characterization of the individual proteins of apoHDL are described elsewhere (6). ApoA-I was isolated by chromatography of apoHDL in 6 M urea on Sephadex G-200 (Pharmacia, superfine) (13). ApoA-II was isolated by chromatography of apoHDL in 6 M'\ urea on DEAE-cellulose (Whatman, DE-52) (6, 12). ApoC-III was isolated as described (27,28). Cleavage with CNBr (Eastman, ratio of reagent to peptide, 500: 1) was performed in 70% formic acid at 250 for 48 hr (29). The resulting peptide fragments of apoA-II were purified to homogeneity by chromatography on Sephadex G-75 (0.2 M Tris*HCI, pH 8.6, 6 M urea); peptides of apoA-I, by chromatography on Biogel P-10 (25% acetic acid). ApoA-I, apoA-IJ, COOH-and

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“…Godici & Lansberger (130) have measured ~3C Tl's and linewidths for phospholipids in the presence of the cholesterol, and also suggested that cholesterol decreases the long range swinging of the acyl chains. The effects of protein on phospholipid motion have also been investigated with ~3C NMR using recombinant lipoprotein/lipid dispersions (131)(132)(133). These studies suggest that lipid-protein interactions are primarily hydrophobic in nature rather than ionic (131,133), and that lipids interacting with protein arc somewhat less mobile than in pure lipid systems (132).…”

Section: Future Prospectsmentioning

confidence: 99%

NMR Studies of Membrane Structure and Dynamics

Bocian¹,

Chan²

1978

Annu. Rev. Phys. Chem.

113

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¹³ C Nuclear Magnetic Resonance Spectroscopy of Native and Recombined Lipoproteins

Abstract: ABSTRACT13C nuclear magnetic-resonance data on native and recombined lipoproteins are reported.

Cited by 38 publications

References 21 publications

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study.

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study.

Lipid-Protein Interactions in High Density Lipoproteins

NMR Studies of Membrane Structure and Dynamics

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13 C Nuclear Magnetic Resonance Spectroscopy of Native and Recombined Lipoproteins

Abstract: ABSTRACT13C nuclear magnetic-resonance data on native and recombined lipoproteins are reported.

Cited by 38 publications

References 21 publications

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study.

Headgroup conformation and lipid--cholesterol association in phosphatidylcholine vesicles: a 31P(1H) nuclear Overhauser effect study.

Lipid-Protein Interactions in High Density Lipoproteins

NMR Studies of Membrane Structure and Dynamics

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About

¹³ C Nuclear Magnetic Resonance Spectroscopy of Native and Recombined Lipoproteins