Two types of hydrocarbon chain interdigitation in sphingomyelin bilayers

Levin, Ira W.; Thompson, T. E.; Barenholz, Y.; Huang, Chunbo

doi:10.1021/bi00343a036

Cited by 154 publications

(111 citation statements)

References 16 publications

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“…[39] The peak-height intensity ratio between the antisymmetric and symmetric bands of the CH 2 groups (I as /I s ) has been demonstrated to be a measure of the order/ disorder parameter of the phospholipid chains in the lipid layer. [57][58][59] The shifts in the peak position of the DPPC alkyl chain CH 2 -asymmetric mode are less than 1 cm À1 from the value measured on water (Fig. S4).…”

Section: àmentioning

confidence: 69%

Impact of anions on the surface organisation of lipid monolayers at the air–water interface

Wang

2017

Environ. Chem.

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Environmental context. Lipids released from lysis of phytoplankton cells are enriched in the sea surface microlayer. Such surface-active organics can be transferred through bursting bubbles to sea-spray aerosols where they can influence atmospheric chemistry. The results presented here suggest that phospholipids combine more readily with SO 4 2À than with Br À , leading to enrichment of organic-coated sulfate salts in marine aerosols.Abstract. Inorganic salts and organic matter are known to be present at higher levels in the sea surface microlayer and marine aerosols; however, the impact of common anions on their surface properties is not well understood. Here, a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayer was enriched with the sodium and ammonium salts of different anions (Br À , Cl À , NO 3 À , SO 4 2À , CH 3 COO À , and HCO 3 À ), and the effects on the surface properties of the monolayer were investigated. The monolayer phase behaviour and the structure of the lipid phases were studied by surface pressure-area (p-A) isotherms and infrared reflection-absorption spectroscopy (IRRAS). The presence of salts in the subphase was found to increase the surface pressure of the DPPC monolayer at a fixed area per molecule. The effect of the anions follows the order of the Hofmeister series. The higher concentration of salt solution caused the p-A isotherm to shift to larger area. The IRRAS spectra demonstrate that the ordering of the DPPC molecules in the liquid condensed phase remains essentially unaffected, even at higher electrolyte concentrations. DPPC molecules combined with SO 4 2À could be transferred from the ocean to sea spray aerosol. The present study finds that the anions have significant influence on the surface organisation and, consequently, the interfacial properties, of the surface-active species at the air-water interface, a finding that has further implications for atmospheric aerosol nucleation.

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Section: àmentioning

confidence: 69%

Impact of anions on the surface organisation of lipid monolayers at the air–water interface

Wang

2017

Environ. Chem.

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“…We have a similar hypothesis for SM and ceramides because the homeostasis of these lipids are critical to both the brain and periphery. SM are important structural compounds that give cells their asymmetric shape and marked curvature [20]; loss of this membrane symmetry is an early event in apoptosis. SM are metabolized into ceramides, second messengers that regulate cellular differentiation, proliferation, and apoptosis [1].…”

Section: Discussionmentioning

confidence: 99%

Serum sphingomyelins and ceramides are early predictors of memory impairment

Mielke¹,

Bandaru²,

Haughey³

et al. 2010

Neurobiology of Aging

164

172

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A blood-based biomarker of Alzheimer's disease (AD) progression could be instrumental in targeting asymptomatic individuals for treatment early in the disease process. Given the direct connection between sphingomyelins (SM), ceramides, and apoptosis, these lipids may be indicators of neurodegeneration and AD progression. Baseline serum SM and ceramides from 100 women enrolled in a longitudinal population-based study were examined as predictors of cognitive impairment. Participants were followed up to 6 visits over 9 years. Baseline lipids, in tertiles, were examined in relation to cross-sectional and incident impairment (<1.5 SD below standard norms) on HVLTimmediate and -delayed memory recall and Trails A and B. SM and ceramides varied in relation to the timing of HVLT-delayed impairment: low levels were associated with cross-sectional impairment; high levels predicted incident impairment in asymptomatic individuals. Lipids were not associated with loss-to-follow-up. Results suggest serum SM and ceramides vary according to the timing of the onset of memory impairment and may be good pre-clinical predictors, or biomarkers, of memory impairment: a deficit observed early in AD pathogenesis.

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“…Third, asymmetric accumulation of bile salts and phosphatidylcholine molecules in the external hemileaflet will generate a local increase in lateral pressure and focal bulging, thereby promoting exovesiculation. Such focal events may be accentuated by the shear resistance of the surrounding sphingomyelin-rich canalicular membrane (27), particularly since sphingomyelin is capable of interdigitating across the membrane bilayer (28). Fourth, the distinct angular junction between the sides of adherent vesicles and the canalicular membrane (Fig.…”

Section: Discussionmentioning

confidence: 99%

Hepatic secretion of phospholipid vesicles in the mouse critically depends on mdr2 or MDR3 P-glycoprotein expression. Visualization by electron microscopy.

Crawford¹,

Smith²,

Hatch³

et al. 1997

J. Clin. Invest.

145

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Hepatocellular secretion of bile salts into the biliary space induces phospholipid and cholesterol secretion, but the mechanism for integrated lipid secretion is poorly understood. Knockout mice unable to make the canalicular membrane mdr2 P-glycoprotein exhibit normal rates of bile salt secretion, yet are virtually incapable of secreting biliary phospholipid and cholesterol. As the mdr2 P-glycoprotein is thought to mediate transmembrane movement of phospholipid molecules, this mouse model was used to examine the mechanism for biliary phospholipid secretion. In wild-type mdr2 ( ϩ / ϩ ) mice, ultrarapid cryofixation of livers in situ revealed abundant unilamellar lipid vesicles within bile canalicular lumina. Although 74% of vesicles were adherent to the external aspect of the canalicular plasma membrane, bilayer exocytosis was not observed. Vesicle numbers in mdr2 ( ϩ / Ϫ ) and ( Ϫ / Ϫ ) mice were 55 and 12% of wild-type levels, respectively. In a strain of mdr2 ( Ϫ / Ϫ ) mice which had been "rescued" by heterozygous genomic insertion of the MDR3 gene, the human homologue of the murine mdr2 gene, vesicle numbers returned to 95% of wild-type levels. Our findings indicate that biliary phospholipid is secreted as vesicles by a process largely dependent on the action of the murine mdr2 P-glycoprotein or human MDR3 P-glycoprotein. We conclude that mdr2-mediated phospholipid translocation from the internal to external hemileaflet of the canalicular membrane permits exovesiculation of the external hemileaflet, a vesiculation process promoted by the detergent environment of the bile canalicular lumen.

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Two types of hydrocarbon chain interdigitation in sphingomyelin bilayers

Cited by 154 publications

References 16 publications

Impact of anions on the surface organisation of lipid monolayers at the air–water interface

Impact of anions on the surface organisation of lipid monolayers at the air–water interface

Serum sphingomyelins and ceramides are early predictors of memory impairment

Hepatic secretion of phospholipid vesicles in the mouse critically depends on mdr2 or MDR3 P-glycoprotein expression. Visualization by electron microscopy.

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