Comment on the carbon-hydrogen stretching region of vibrational raman spectra of phospholipids

Bunow, Margaret R.; Levin, Ira W.

doi:10.1016/0005-2760(77)90015-7

Cited by 94 publications

(56 citation statements)

References 12 publications

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“…Although the intensity of this band increases with melting of the fatty acid chain, I2926/I2850 in pure lipid liposomes does not exceed 1.0 (28,29). Moreover, we have demonstrated that applied cation gradients do not alter this ratio in pure lipid vesicles.…”

Section: Discussionmentioning

confidence: 99%

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Effect of transmembrane ion gradients on Raman spectra of sealed, hemoglobin-free erythrocyte membrane vesicles.

Mikkelsen¹,

Verma²,

Wallach³

1978

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

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Sealed hemoglobin-free erythrocyte vesicles have been isolated. Imposition of transmembrane cation gradients increases the intensity of Raman scattering in the CH3-stretching region as observed with unsealed ghosts at temperatures >38°C and pH <7.0 [Verma, S. P. & Wallach, D. F. H. (1976) Proc. Natl Acad. Sci. USA 73, in the amide I and amide III frequencies consistent with increased helicity of membrane proteins are observed upon imposition of a cation gradient. Spectrin-free vesicles also demonstrate cation gradient-sensitive intensity changes in the CH3-stretching region. However, no evidence for cation gradient-related protein conformation changes is found with these vesicles. The transmembrane potential of these vesicles has been altered by variations in anion composition and the electrogenic activity of Na+,K+-ATPase. The membrane potential was monitored by cyanine dye fluorescence. Imposition of a membrane potential (negative inside) also increased the intensity of Raman scattering in the CH3-stretching region. These results suggest that a transmembrane potential (negative inside) and/or cation gradient can energize membranes by compression of the apolar region and transfer of protein methyl residues into polar regions.Erythrocyte membranes undergo pH-sensitive thermotropic changes of state at near physiological temperatures (1-7): in whole cells, membrane elastic area-compressibility shifts abruptly near 45°C (1) and membrane potential breaks down near 41°C (2). In ghosts, tryptophan fluorescence can be quenched by nitroxide analogs of stearic acid (3, 4) in a manner indicating that the protein fluorophores become abruptly more accessible about 370C. This process is reversible below 42°C and shifts to lower temperatures upon pH reduction. Electron spin resonance studies (5) with nitroxide-labeled lipids and erythrocyte membranes also demonstrate a pH-sensitive thermal transition at 37.5-40.50C. Proton magnetic resonance (6) shows that methyl side chains of membrane proteins become more mobile as the temperature is raised above about 350C. Raman spectroscopy (7) reveals a sharp, thermotropic pHsensitive discontinuity in the membrane protein CHs-stretching signal, which at pH 7.0-7.5 has a lower limit of 380C and is irreversible above 420C (7). Reduction of pH to 6.5 lowers the transition temperature by about 160C (7). Raman spectra during thermally induced unfolding of ribonuclease at acid pH and evaluation of model compounds indicate that the thermotropism of the methyl-stretching signals arises from the transfer of side-chain methyl groups from apolar to more polar regions (8). We now show that transmembrane ionic gradients across hemoglobin-free, erythrocyte membrane vesicles influence membrane protein Raman signals. EXPERIMENTALAll chemicals were of the highest purity grade available. Hepes, valinomycin, ATP (Na+), and ouabain were obtained from Sigma (St. Louis, MO), 2H20 from New England Nuclear (Boston, MA), egg lecithin from Lipid Products (United Kingdom), and reagents for the synthesis ...

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Section: Discussionmentioning

confidence: 99%

“…The second contribution at 2926 cm-1 has been assigned to assymmetric CH2-stretching of lipids (28,29). Although the intensity of this band increases with melting of the fatty acid chain, I2926/I2850 in pure lipid liposomes does not exceed 1.0 (28,29).…”

Section: Discussionmentioning

confidence: 99%

Effect of transmembrane ion gradients on Raman spectra of sealed, hemoglobin-free erythrocyte membrane vesicles.

Mikkelsen¹,

Verma²,

Wallach³

1978

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

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“…Figure 6a shows a typical Raman spectrum of phospholipids in the C-H stretching region. The two dominant bands at 2850 and 2880 cm −1 arise from the symmetric and asymmetric C-H stretching modes, respectively, of the CH 2 moieties of the hydrocarbon chains of the fatty acyl group, whereas the band near 2935 cm −1 is attributed to the symmetric C-H stretching mode of the terminal CH 3 groups of these chains in the hydrophobic centre of the bilayer [4,18,35].…”

Section: Peptide-phospholipid Interactions In Liposomesmentioning

confidence: 99%

Vibrational spectroscopy applied to the study of milk proteins

Li‐Chan¹

2007

Lait

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-Vibrational spectroscopy is a versatile tool for analysis of foods including dairy products. This paper provides an overview of techniques that may be useful to study structural properties and interactions of milk proteins. Specific examples of recent research conducted in our laboratory using Raman, micro-Raman and FT-Raman spectroscopy will be described to illustrate their applications for investigating protein-protein, protein-lipid, and protein-polysaccharide interactions, and for elucidating structure-function relationships of whey proteins and peptides. Raman spectroscopy was used to discriminate between structural changes of β-lactoglobulin in transparent fine-stranded versus particulate gels. Formation of particulate gel structures led to a more hydrophilic or exposed microenvironment around tryptophan residues, compared to a more hydrophobic microenvironment in translucent gels. A decrease in the α-helical content was more pronounced in translucent gels, while both types of gels retained considerable β-sheet structures, consistent with the known heat-resistance of the β-barrel structure of β-lactoglobulin. Principal component similarity analysis demonstrated that heat treatment and heat-κ-carrageenan interactions were the most influential factors affecting whey protein structure as monitored by spectral changes. Raman micro-spectroscopy was applied to investigate protein-lipid interactions at the interface between bovine serum albumin solution and mineral or corn oil. While Raman bands assigned to aromatic and aliphatic residues inferred involvement of hydrophobic interactions at the oil-water interface, the secondary structure was not significantly altered. Temperature-dependent changes in the Raman C-H stretching region of liposomes composed of phospholipids with varying headgroups and acyl chains were influenced by the presence of bovine lactoferricin. This approach may be useful to elucidate the interactions of cationic antimicrobial peptides with bacterial versus host cell membranes. A diverse range of other applications as well as new developments in techniques are emerging in the literature, indicating the potential for increasing use of vibrational spectroscopy in the analysis of milk and milk products. Résumé -Spectroscopie vibrationnelle appliquée à l'étude des protéines. La spectroscopie vibrationnelle est un outil adéquat pour l'analyse des aliments, dont des produits laitiers. Cet article présente une revue des techniques qui peuvent être utiles pour étudier les propriétés structurales et les interactions entre protéines laitières. Des exemples spécifiques de recherches récentes conduites dans notre laboratoire utilisant la spectroscopie Raman, micro-Raman et FT-Raman sont décrites pour illustrer leurs applications dans l'étude des interactions protéines/protéines, protéines/lipides et protéines/polysaccharides, et dans l'élucidation des relations structure/fonction des protéines et peptides du lactosérum. La spectroscopie Raman a été utilisée pour faire la distinction entre les c...

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“…The first (2925 cm 1 is the symmetric CH stretching vibration of the end chain methyl groups [ s (CH 3 )] and the second (2935 cm 1 ) is an infrared-active band (Raman inactive) that becomes Raman active upon heating owing to symmetry changes as the lipid chains go from the all-trans conformation to conformations containing gauche bonds. 17 These ratios are useful to follow the phase transitions and highly sensitive to interchain interactions, 18 but r is also influenced by the mobility of the methyl end chain terminal. Chain melting can be analyzed plotting r or R versus temperature, as I 2880 decreases (with respect to I 2850 and I 2935 upon heating.…”

Section: Effect Of Phytol On Dppc Multilayersmentioning

confidence: 99%

Raman and Fourier transform infrared study of phytol effects on saturated and unsaturated lipid multibilayers

Picquart

Lefèvre

2002

J Raman Spectroscopy

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The effects of phytol on DPPC and OPPC multilayers were investigated using FT-IR and Raman spectroscopy. The results were compared with those obtained with a-tocopherol (a-T) and a-tocopherol acetate (a-TA). The chain packing was analyzed using Raman intensity ratios measured in the CH 2 stretching region, whereas the number of gauche bonds introduced by phytol was estimated by the measure of the FT-IR absorbance of the CH 2 wagging progression modes. It is shown that the chain packing is reduced and that gauche rotamer formation is promoted by phytol in the gel phase. Phytol has a very similar effect on the acyl chains of DPPC to a-T but does not have the same impact on the C O stretching vibrations of this lipid. The results indicate that phytol perturbs the interfacial region of DPPC causing dehydration or a conformational modification of the ester groups. Furthermore, the modification of the OPPC chain order induced by phytol is slightly different with respect to a-T. It is concluded that (1) a hydrogen bond between the hydroxyl group of a-T and the phospholipid carbonyl groups may not necessarily be associated with the stabilization of the membrane, (2) the studied phytyl compounds may be located more or less close to the membrane interface, (3) the presence of the chromanol ring may strongly influence the location of vitamin E within the membrane and, consequently, its capacity to catch free radicals and (4) the hydroxyl group, chroman moiety and phytyl chain all play a crucial role that determines the effects of a-T on lipid acyl chains and its location within membranes, which in turn can affect its biological function.

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Comment on the carbon-hydrogen stretching region of vibrational raman spectra of phospholipids

Cited by 94 publications

References 12 publications

Effect of transmembrane ion gradients on Raman spectra of sealed, hemoglobin-free erythrocyte membrane vesicles.

Effect of transmembrane ion gradients on Raman spectra of sealed, hemoglobin-free erythrocyte membrane vesicles.

Vibrational spectroscopy applied to the study of milk proteins

Raman and Fourier transform infrared study of phytol effects on saturated and unsaturated lipid multibilayers

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