Configurational statistics of acyl chains in polyunsaturated lipid bilayers from deuterium NMR

Salmon, Amir; Dodd, Steven W.; Williams, Gerald D.; Beach, J. M.; Brown, Michael F.

doi:10.1021/ja00243a010

Cited by 115 publications

(153 citation statements)

References 5 publications

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“…While the thermal properties of the Lp to La transition are similar for ether-and ester-linked phospholipids, ether lipids exhibit polymorphisms in the gel state, including the formation of interdigitated phases (41,42). It has also been suggested from 2H NMR studies that 1-palmitoyl, 2-docosahexaenoyl phosphatidylcholine may form interdigitated phases in the La state (43).…”

Section: Discussionmentioning

confidence: 99%

Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry.

Wolf

Maynard

McKinnon

et al. 1990

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

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Mammalian sperm plasma membranes, in contrast to those of mammalian somatic cells, exhibit a significant fraction of lipid that does not diffuse laterally in the plane of the membrane. This nondiffusing fraction results from lipid-ipid interactions. Similar nondiffusing fractions are found in mixed-lipid model systems that contain coexistent gel and fluid domains. These results suggest that the sperm plasma membrane may also exhibit lateral phase segregations of lipids and may contain significant amounts of gel-phase lipid. In this paper we use differential scanning calorimetry to show that, in contrast to the plasma membranes of mammalian somatic cells, the plasma membrane from the anterior region of the head of ram sperm exhibits at least two major endothermic transitions, one centered at -260C and one centered at 60°C. The heats of these transitions are consistent with gel-to-fluid transitions in model membranes. These transitions are observed both in plasma membrane vesicles and in rehydrated lipid extracts made from these vesicles. These results demonstrate that at physiological temperatures the lipids of the ram sperm plasma membrane are segregated into coexistent fluid and gel domains.

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Section: Discussionmentioning

confidence: 99%

Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry.

Wolf

Maynard

McKinnon

et al. 1990

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

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“…It is well documented that the presence of Chol in a membrane, including reconstituted membranes containing the nAChR (7), leads to an ordering of the fatty acyl chains and thus a decrease in fluidity (20). Although the effects of DOPA on the physical properties of EPC membranes are not well characterized, it is possible that the very small head group leads to a lateral condensation of the lipid acyl chains and thus an increased ordering of the lipid bilayer (21,22). In support of the latter, it has been shown that increasing levels of DOPA in reconstituted EPC membranes lead to a decrease in the proportion of lipid ester carbonyls that are hydrogen-bonded to water, which could correspond to a decreased penetration of water into the lipid head group region of the bilayer as a result of a lateral condensation of the phospholipids (23).…”

Section: CMmentioning

confidence: 99%

Effect of Membrane Lipid Composition on the Conformational Equilibria of the Nicotinic Acetylcholine Receptor

Baenziger

Morris

Darsaut

et al. 2000

Journal of Biological Chemistry

140

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The effects of cholesterol (Chol) and an anionic lipid, dioleoylphosphatidic acid (DOPA) on the conformational equilibria of the nicotinic acetylcholine receptor (nAChR) have been investigated using Fourier transform infrared difference spectroscopy. The difference between spectra recorded in the presence and absence of agonist from the nAChR reconstituted into 3:1:1 egg phosphatidylcholine (EPC)/DOPA/Chol membranes exhibits positive and negative bands that serve as markers of the structural changes associated with the resting to desensitized conformational change. These markers are absent in similar difference spectra recorded from the nAChR reconstituted into EPC membranes lacking both Chol and DOPA, indicating that the nAChR cannot undergo conformational change in response to agonist binding. When low levels of either Chol or DOPA up to 25 mol % of the total lipid are included in the EPC membranes, the markers suggest the predominant stabilization of a conformation that is a structural intermediate between the resting and desensitized states. At higher levels of either Chol or DOPA, the nAChR is stabilized in a conformation that is capable of undergoing agonistinduced desensitization, although DOPA appears to be required for the nAChR to adopt a conformation fully equivalent to that found in native and 3:1:1 EPC/DOPA/ Chol membranes. The ability of these two structurally diverse lipids, as well as others (Ryan, S. E., Demers, C. N., Chew, J. P., Baenziger, J. E. (1996) J. Biol. Chem. 271, 24590 -24597), to modulate the functional state of the nAChR suggests that lipids act on the nAChR via an indirect effect on some physical property of the lipid bilayer. The data also suggest that anionic lipids are essential to stabilize a fully functional nAChR. We propose that membrane fluidity modulates the relative populations of nAChRs in the resting and desensitized states but that subtle structural changes in the presence of anionic lipids are essential for full activity.

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“…Chol has a well characterized ordering effect on lipid bilayers in the liquid-crystalline state. The very small head group of DOPA should lead to a condensation and thus a restriction in the amplitudes of motion of the fatty acyl chains and thus a more ordered, less fluid lipid bilayer (26,27). The presence of both lipids could lead to a relatively ordered lipid membrane that might be required for maintaining the nAChR in a predominantly resting conformation.…”

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confidence: 99%

Structural Effects of Neutral and Anionic Lipids on the Nicotinic Acetylcholine Receptor

Ryan

Demers

Chew

et al. 1996

Journal of Biological Chemistry

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The effects of both neutral and anionic lipids on the structure of the nicotinic acetylcholine receptor (nAChR) have been probed using infrared difference spectroscopy. The difference between infrared spectra of the nAChR recorded using the attenuated total reflectance technique in the presence and absence of the neurotransmitter analog, carbamylcholine, exhibits a complex pattern of positive and negative bands that provides a spectral map of the structural changes that occur in the nAChR upon ligand binding and subsequent desensitization. This spectral map is essentially identical in difference spectra recorded from native, native alkaline-extracted, and affinity-purified nAChR reconstituted into either soybean asolectin or egg phosphatidylcholine membranes containing both neutral and anionic lipids. This result suggests both a similar structure of the nAChR and a similar resting to desensitized conformational change in each membrane environment. In contrast, difference spectra recorded from the nAChR reconstituted into egg phosphatidylcholine membranes lacking neutral and/or anionic lipids all exhibit an essentially identical pattern of band intensity variations, which is similar to the pattern of variations observed in difference spectra recorded in the continuous presence of the desensitizing local anesthetic, dibucaine. The difference spectra suggest that the main effect of both neutral and anionic lipids in a reconstituted egg phosphatidylcholine membrane is to help stabilize the nAChR in a resting conformation. In the absence of neutral and/or anionic lipids, the nAChR is converted into an alternate conformation that appears to be analogous to the local anesthetic-induced desensitized state. Significantly, the proportion of receptors found in the resting versus the putative desensitized state appears to be dependent upon the final lipid composition of the reconstituted membrane. A lipid-dependent modulation of the equilibrium between a channel-active resting and channel-inactive desensitized state may account for the modulations of nAChR activity that are observed in different lipid membranes.

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Configurational statistics of acyl chains in polyunsaturated lipid bilayers from deuterium NMR

Cited by 115 publications

References 5 publications

Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry.

Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry.

Effect of Membrane Lipid Composition on the Conformational Equilibria of the Nicotinic Acetylcholine Receptor

Structural Effects of Neutral and Anionic Lipids on the Nicotinic Acetylcholine Receptor

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