The molecular structure of lecithin dihydrate

Pearson, R. H.; Pascher, I.

doi:10.1038/281499a0

Cited by 641 publications

(523 citation statements)

References 15 publications

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“…The headgroup spacing D HH is defined as the distance between the two peaks in the electron density profile and is usually supposed to be a good approximation to the phosphatephosphate thickness of the bilayer (Pearson and Pascher, 1979). D HH is the same, of course, for the relative and the absolute electron density profiles.…”

Section: Headgroup Spacing D Hhmentioning

confidence: 99%

Fluid phase structure of EPC and DMPC bilayers

Petrache

Tristram-Nagle

Nagle

1998

Chemistry and Physics of Lipids

243

236

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X-ray diffraction data taken at high instrumental resolution were obtained for EPC and DMPC under various osmotic pressures, primarily at T = 30°C. The headgroup thickness D HH was obtained from relative electron density profiles. By using volumetric results and by comparing to gel phase DPPC we obtain areas and . The analysis also gives estimates for the areal compressibility K A . The A F results lead to other structural results regarding membrane thickness and associated waters. Using the recently determined absolute electrons density profile of DPPC, the A F results also lead to absolute electron density profiles and absolute continuous transforms |F(q)| for EPC and DMPC. Limited measurements of temperature dependence show directly that fluctuations increase with increasing temperature and that a small decrease in bending modulus K c accounts for the increased water spacing reported by Simon et al. (1995) Biophys. J. 69, 1473−1483.

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Section: Headgroup Spacing D Hhmentioning

confidence: 99%

Fluid phase structure of EPC and DMPC bilayers

Petrache

Tristram-Nagle

Nagle

1998

Chemistry and Physics of Lipids

243

236

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“…49. B, the crystallographically observed cPLA 2 C2 domain structure was placed onto the crystal structure of a dimyristoyl-PC monolayer (one layer from the bilayer crystal structure is shown) (50). The crystal structure of the dimyristoyl-PC has the lipids arranged in two staggered levels.…”

Section: Table Imentioning

confidence: 99%

Mapping the Phospholipid-binding Surface and Translocation Determinants of the C2 Domain from Cytosolic Phospholipase A2

Perišić¹,

Paterson²,

Mosedale³

et al. 1999

Journal of Biological Chemistry

120

112

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Cytosolic phospholipase A 2 (cPLA 2 ) plays a key role in the generation of arachidonic acid, a precursor of potent inflammatory mediators. Intact cPLA 2 is known to translocate in a calcium-dependent manner from the cytosol to the nuclear envelope and endoplasmic reticulum. We show here that the C2 domain of cPLA 2 alone is sufficient for this calcium-dependent translocation in living cells. We have identified sets of exposed hydrophobic residues in loops known as calcium-binding region (CBR) 1 and CBR3, which surround the C2 domain calcium-binding sites, whose mutation dramatically decreased phospholipid binding in vitro without significantly affecting calcium binding. Mutation of a residue that binds calcium ions (D43N) also eliminated phospholipid binding. The same mutations that prevent phospholipid binding of the isolated C2 domain in vitro abolished the calcium-dependent translocation of cPLA 2 to internal membranes in vivo, suggesting that the membrane targeting is driven largely by direct interactions with the phospholipid bilayer. Using fluorescence quenching by spin-labeled phospholipids for a series of mutants containing a single tryptophan residue at various positions in the cPLA 2 C2 domain, we show that two of the calcium-binding loops, CBR1 and CBR3, penetrate in a calcium-dependent manner into the hydrophobic core of the phospholipid bilayer, establishing an anchor for docking the domain onto the membrane.Cytosolic phospholipase A 2 (cPLA 2 ) 1 is an 85-kDa protein that hydrolyzes phospholipids containing arachidonate at the sn-2 position (Refs. 1 and 2; reviewed in Refs. 3-6). This enzyme has no sequence homology to any other phospholipase A 2 and is capable of functioning in receptor-regulated, agonistinduced arachidonic acid release (7,8). Recent work with mice lacking a gene for cPLA 2 has demonstrated that cPLA 2 has a critical, nonredundant role in the production of eicosanoids and platelet-activating factor in the process of inflammation, anaphylaxis, and reproduction (9, 10). The activity of cPLA 2 is regulated by calcium; however, the role of calcium is to promote membrane binding rather than participating in catalysis directly. An increase in intracellular calcium triggered by calcium ionophores or agonists such as histamine or IgE/antigen causes the translocation of cPLA 2 from the cytosol to the nuclear membrane and endoplasmic reticulum (11)(12)(13)(14), where it co-localizes with other enzymes involved in eicosanoid metabolism, such as prostaglandin-endoperoxide synthase-1 and -2, 5-lipoxygenase, and 5-lipoxygenase-activating protein (11, 15). The activity of cPLA 2 is also regulated via phosphorylation of the enzyme, and for at least some agonists, phosphorylation of cPLA 2 is a requisite step in its activation (4, 5). Detailed studies of the role of calcium and phosphorylation in arachidonic acid release have shown that a sustained increase in intracellular calcium is sufficient to induce arachidonic acid release, whereas either sustained phosphorylation of cPLA 2 or a transient ...

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“…The carbonyl stretching line-shapes in membranes could yield direct information about molecular architecture and fluctuations in the membrane interface (10, 11), provided that the origin of the spectral inhomogeneity of the carbonyl IR response in phospholipid membranes is understood. The inhomogeneity was attributed to differences in the local environment of the sn-1 and sn-2 carbonyl moieties stemming from the packing arrangements (6, 8), the local chain conformations (8,9,(12)(13)(14), the relative positions of the two CAO groups with respect to the interface (9, 15), and the degree of hydration (16,17). In an elegant work, Blume et al (16) ruled out all of the scenarios involving local structural differences except hydrogen bonding.…”

mentioning

confidence: 99%

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

Volkov¹,

Chelli

Zhuang

et al. 2007

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

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The inter-and intramolecular interactions of the carbonyl moieties at the polar interface of a phospholipid membrane are probed by using nonlinear femtosecond infrared spectroscopy. Twodimensional IR correlation spectra separate homogeneous and inhomogeneous broadenings and show a distinct cross-peak pattern controlled by electrostatic interactions. The inter-and intramolecular electrostatic interactions determine the inhomogeneous character of the optical response. Using molecular dynamics simulation and the nonlinear exciton equations approach, we extract from the spectra short-range structural correlations between carbonyls at the interface.carbonyl ͉ interface ͉ intermolecular ͉ nonlinear exciton equations ͉ molecular dynamics A s a constituent organelle in a cell, the membrane sets the information and energy gradients necessary for life. Carbonyl, phosphate, and choline are the common structural moieties in the polar surface of cellular membranes (1), mediating molecular recognition and signal transduction (1-4). Unfortunately, our knowledge on their arrangement and dynamics is rather limited due to experimental difficulties. In a lipid bilayer, lateral irregularity smears the diffraction pattern in neutron scattering measurements, and NMR resonances are broad because of the restricted motions that result in incomplete motional narrowing. IR spectroscopy, on the other hand, is known to be helpful in application to such systems. Since 1972, the IR resonance of carbonyl moieties in phospholipid membranes has attracted considerable attention (5-9). The absorption band shows a clear inhomogeneous character and can be described as a superposition of several substates (5-7). The carbonyl stretching line-shapes in membranes could yield direct information about molecular architecture and fluctuations in the membrane interface (10, 11), provided that the origin of the spectral inhomogeneity of the carbonyl IR response in phospholipid membranes is understood. The inhomogeneity was attributed to differences in the local environment of the sn-1 and sn-2 carbonyl moieties stemming from the packing arrangements (6, 8), the local chain conformations (8,9,(12)(13)(14), the relative positions of the two CAO groups with respect to the interface (9, 15), and the degree of hydration (16,17). In an elegant work, Blume et al. (16) ruled out all of the scenarios involving local structural differences except hydrogen bonding. In a recent study, we eliminated the variance in hydration as a possible source of inhomogeneity (18).Here we employ 2D IR spectroscopy (19,20) to explore whether and to what extent the inhomogeneities of the carbonyl absorption can be attributed to electric field fluctuations. 2D IR techniques are femtosecond optical analogues of 2D NMR that generate 2D correlation plots that can separate homogeneous and inhomogeneous broadenings along the diagonal and antidiagonal axis and provide a rich cross-peak pattern (21). Electrostatic interactions strongly contribute to the optical response of molecular crystals (2...

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The molecular structure of lecithin dihydrate

Cited by 641 publications

References 15 publications

Fluid phase structure of EPC and DMPC bilayers

Fluid phase structure of EPC and DMPC bilayers

Mapping the Phospholipid-binding Surface and Translocation Determinants of the C2 Domain from Cytosolic Phospholipase A2

Electrostatic interactions in phospholipid membranes revealed by coherent 2D IR spectroscopy

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