Hydrocarbon Chain Conformation Research Articles

Raman spectroscopic studies of the dipalmitoylphosphatidylcholine/glucagon and the dipalmitoylphosphatidylcholine/cardiolipin/insulin systems

AbstractThe phospholipid hydrocarbon chain conformation has been measured in lipid/protein complexes of dipalmitoylphosphatidylcholine (DPPC)/glucagon and dipalmitoylphosphatidylcholine/cardiolipin/insulin using the conformation‐sensitive CH stretching region of the Raman spectrum as a probe. In the DPPC/glucagon complex, which models hydrophobic interactions between (membrane) proteins and phospholipids, the Raman data show that the lateral interactions between phospholipid hydrocarbon chains have been greatly disrupted in the complex. The primary effect of the protein appears to be to induce a disordering of the phospholipid. The gel–liquid crystal phase transition of DPPC is reduced in temperature and is rendered less cooperative. In the DPPC/cardiolipin/insulin complex, which models the electrostatic interaction between peripheral membrane proteins and phospholipids, the primary effect of complexation is to rigidify and order the hydrocarbon chains of the phospholipids. The main interaction of the protein occurs with the cardiolipin and results in the neutralization of the excess charge. The ternary complex undergoes a broad phase separation not present in the binary phospholipid mixture.

A Study of the Amylose‐Monoglyceride Complex by Raman Spectroscopy

AbstractThe interaction between monostearin and amylose in an aqueous environment has been studied by Raman spectroscopy. A perdeuterated lipid was used to follow the C‐D stretching vibrations. The hydrocarbon chain conformation inside the amylose helix seems to be ordered as in the crystalline state, and the geometry of the amylose V‐form of this complex corresponds to nearly three turns of the helix per hydrocarbon chain. The maximal amount of monoglyceride in the complex (1: 5 monoglyceride: amylose) obtained experimentally, indicates that not the whole chain is in the average involved in complex formation.

On the structure of smectic S H and S m phases of HxBPA

On the basis of theoretical considerations and Raman data it is shown that in the smectic H phase of HxBPA many more conformations of hydrocarbon chains are allowed than in the S m phase. It is proposed that these chains are rotating around the single bonds in the S H phase. A theoretical model is developed for the forces which lead to the transitions S H → S m. The model combines de Vries' model with quadrupole interaction between chains.

A Raman spectroscopy study of micellar structures in ternary systems of water-sodium octanoate-pentanol/decanol

Raman spectroscopy has been used in order to study the micellar structure of the systems water-sodium octanoate-pentanol and water-sodium octanote-decano. The C—H and C—C stretching vibration regions have been utilized in the study of both the hydrocarbon chain conformation and the degree of polar/apolar contact. In sodium octanoate solutions there seems to be a successive increase in thetrans-conformation up tocmc, and then thetrans/gauche ratio is fairly constant. Sodium octanoate micelles with solubilized pentanol and decanol were examined by using perdeuterated octanoate and water in order to avoid overlapping in the contributions from each component in the spectra. Both pentanol and decanol have the same effect in reducing the contracts between water and hydrocarbon chains. The chain conformation in the micelles is influenced by incorporation of pentanol in the same way as if the octanoate concentration is increased, whereas on the other side decanol influences thetrans/gauche ratio of the hydrocarbon chains. The inverted micelles, considered to consist of water aggregates in a lipophilic environment, were also examined. The strongest structural effects with ragard to waterhydrocarbon chain contact were seen when the water/soap ratio varied. When the soap content is increased in the pentanol system thetrans-conformation seems to increase, whereas the degree ofgauche-conformation increases when the soap concentration is increased in the decanol system.

ChemInform Abstract: PHOTOCHEMICAL PROBES OF HYDROCARBON CHAIN CONFORMATION IN SOLUTION

Chemischer InformationsdienstVolume 8, Issue 39 Physical Organic Chemistry ChemInform Abstract: PHOTOCHEMICAL PROBES OF HYDROCARBON CHAIN CONFORMATION IN SOLUTION M. A. WINNIK, M. A. WINNIKSearch for more papers by this author M. A. WINNIK, M. A. WINNIKSearch for more papers by this author First published: September 27, 1977 https://doi.org/10.1002/chin.197739051Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume8, Issue39September 27, 1977 RelatedInformation

Order-disorder conformation transition of hydrocarbon chains in lipopolysaccharide from Escherichia coli.

Thermal phase transitions in isolated lipopolysaccharide from Escherichia coli B/r have been studied using N-phenyl-1-naphthylamine as fluorescence indicator and by X-ray diffraction analyses. Measurements of fluorescence changes revealed a transition temperature tt of 22°C with a range of transition of 10.5°C. Wide-angle X-ray diffraction analyses showed that lipopolysaccharide in aqueous suspension forms a lipid bilayer in which, below tt, the ordered state of hydrocarbon chains is less well developed than in most biological membranes or lipids; instead of the 0.42-nm reflection attributable to the β-type ordered conformation of hydrocarbon chains, a 0.433-nm reflection was found in lipopolysaccharide. Thermal phase transitions probably depending on lipopolysaccharide and as measured with N-phenyl-1-naphthylamine were found in some cell envelope preparations (tt∼ 25–29°C) while others did not exhibit phase transitions; in the latter cases EDTA treatment evoked the appearance of such transitions. It was not possible to decide if these transitions were due to lipopolysaccharide-phospho-lipid interaction because studies with model systems were not successful: temperature-dependent fluorescence changes in mixed phospholipid-lipopolysaccharide preparations only revealed the two separated lipopolysaccharide and phospholipid transitions. Addition of dimyristoyl phosphatidylethanolamine (tt= 48°C) to cell envelopes (tt∼ 33°C) of a heptose-less mutant of E. coli K-12 led to the appearance of only one new tt at 42°C. It appears that external phospholipid can be incorporated into the altered outer membrane of the mutant and there interact with lipopolysaccharide.

Photochemical probes of hydrocarbon chain conformation in solution

Photochemical probes of hydrocarbon chain conformation in solution

Conformational and configurational analysis of hydrocarbon chains based on time-averaged carbon-13 chemical shifts

The conformations of saturated hydrocarbon chains are analysed by a least-squares fit of calculated to observed time-averaged carbon-13 chemical shifts. The calculated resonances are the sums of products of conformer resonances and conformer probabilities. The conformer shieldings are derived with predictive parameters developed earlier for conformationally well defined systems. The conformer probabilities are taken to be products of rotamer probabilities. The rotamer probabilities are variables in the analysis.

A Raman spectroscopic study of the Aerosol OT-water system

A detailed Raman spectroscopic study of the bis-(di-2-ethylhexyl)sodium sulphosuccinate (Aerosol OT)-water system has been carried out at ambient temperature (20 ± 2° C). Marked changes were observed in the relative intensity of the band at 1460 cm −1 when the concentration of Aerosol OT was varied. Depolarisation ratio measurements on the viscous isotropic cubic phase indicate that this intense band at 1460 cm −1 is largely associated with the antisymmetric methylene rocking/deformation modes. Moreover, this was the only spectral region to vary with Aerosol OT concentration. A plot of I 1460/I 1734 versus Aerosol OT concentration indicated that the most striking changes in the intensity of the 1460 cm −1 band occurred in the regions where large changes or anomalies have been previously observed (a) in the observed X-ray spacings for one-dimensional swelling, (b) in the conductivity and (c) in the optical birefringence. The results of this Raman spectroscopic study therefore indicate the following. 1. (a) The methylene deformation region of the Raman spectrum at 1400–1500 cm −1 gives direct information on the chain packing arrangements of the hydrocarbon chains in the molecule in the liquid crystalline phase, as has previously been shown in the crystalline phase. Thus Raman spectroscopy is very useful for detecting changes in the hydrocarbon chain conformation within the lamellar (and possibly other) mesophase(s). 2. (b) The physical changes observed within the lamellar mesophase are associated with a chain reorganisation whereby the two branches of the hydrocarbon chains may separate in the concentration regions where the intensity ratio I 1460/I 1734 versus Aerosol OT content is a minimum. Thus, either chain reorientation occurs in several regions of the lamellar mesophase or the changes observed by the various physical techniques mentioned above may show possible phase transitions occurring within the lamellar region previously believed to be homogeneous.

Deuterated fatty acids as Raman spectroscopic probes of membrane structure

Raman spectra are reported for the C-D stretching region of stearic acid- d 35 bound in egg lecithin multilayers. The temperature dependence of the spectra shows that the linewidth of the C-D stretching bands is a sensitive and non-perturbative probe of membrane hydrocarbon chain conformation. The utility of this approach for studying lipid conformation in membranes containing a significant fraction of non-lipid component is discussed.

Deuterated fatty acids as Raman spectroscopic probes of membrane structure

Raman spectra are reported for the C-D stretching region of stearic acid- d 35 bound in egg lecithin multilayers. The temperature dependence of the spectra shows that the linewidth of the C-D stretching bands is a sensitive and non-perturbative probe of membrane hydrocarbon chain conformation. The utility of this approach for studying lipid conformation in membranes containing a significant fraction of non-lipid component is discussed.

Raman spectroscopic studies of the effect of some of the gramicidin antibiotics on the phospholipid bilayer

AbstractThe vibrational Raman spectra of some Gramicidin antibiotics and Gramicidin/lipid/water systems are reported. From comparison of these spectra some information can be obtained regarding changes in the tertiary structure of the antibiotic and changes in the hydrocarbon chain conformation within the bilayer on formation of the antibiotic/lipic/water complex.

Phosphorescence of substituted benzophenones in solution. A probe of hydrocarbon chain conformation in three nonpolar solvents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphorescence of substituted benzophenones in solution. A probe of hydrocarbon chain conformation in three nonpolar solventsMitchell A. Winnik, Soumyendu N. Basu, Chung Kwong Lee, and Douglas S. SaundersCite this: J. Am. Chem. Soc. 1976, 98, 10, 2928–2935Publication Date (Print):May 1, 1976Publication History Published online1 May 2002Published inissue 1 May 1976https://doi.org/10.1021/ja00426a042RIGHTS & PERMISSIONSArticle Views122Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (856 KB) Get e-Alerts Get e-Alerts

Phosphorescence of substituted benzophenones in solution. Probes for the conformation of hydrocarbon chains in polar and protic solvents

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphorescence of substituted benzophenones in solution. Probes for the conformation of hydrocarbon chains in polar and protic solventsMitchell A. Winnik, Alberta Lemire, Douglas S. Saunders, and Chung Kwong LeeCite this: J. Am. Chem. Soc. 1976, 98, 7, 2000–2002Publication Date (Print):March 1, 1976Publication History Published online1 May 2002Published inissue 1 March 1976https://doi.org/10.1021/ja00423a076RIGHTS & PERMISSIONSArticle Views82Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (363 KB) Get e-Alerts Get e-Alerts

The effect of sonication on the hydrocarbon chain conformation in model membrane systems: A Raman spectroscopic study

Raman spectra are presented for egg lecithin above and below the gel-liquid crystal phase transition, and several regions of the Raman spectrum are shown to be sensitive to conformational changes in the hydrocarbon chains. These regions are used to investigate the effect of sonication on the structure of egg lecithin and dipalmitoyl lecithin vesicles. Sonication of both egg lecithin above T m , and dipalmitoyl lecithin above and below T m produces no change in the relative population of trans and gauche isomers in any of the systems studied. Sonication does however appear to effect interchain interactions, a possible consequence of imperfect packing towards the center of the bilayers in vesicle systems.

Molecular orbital studies on the conformation of phospholipids. II. Preferred conformations of hydrocarbon chains and molecular organization in biomembranes

The preferred conformations of the nonpolar β and γ (hydrocarbon) chains in phospholipids have been derived using EHT and CNDO calculations. These calculations indicate that the possible conformations of phospholipids are highly restricted. The calculations find support from X-ray diffraction studies and NMR measurements on model compounds. When considering conformations relevant to structures in cell membranes, a further selection is possible because of the fact that in aqueous solutions hydrophobic interactions stabilize an arrangement where the hydrocarbon chains (β and γ) are stacked almost parallel to one another, leading to a bilayer structure. The various models for β and γ-chains which satisfy this condition have been compared and it has been shown that of these only four are favoured by energy considerations. These arrangements differ from one another in the orientation of the β-chain and γ-chains in the interior of the bilayer structure. A low energy pathway connects these conformations and thus the molecule can easily flip from one stable bilayer arrangement to another. The possible conformations of the polar group (α) are likewise restricted. The proposed model provides explanations to a number of dynamic and static properties of phospholipids, in particular to the observed NMR coupling constants, 1H and 13C relaxation times, studies based on ESR spin labels and the observed X-ray diffraction results on model compounds.

ChemInform Abstract: THE RAMAN SPECTRA AND MOLECULAR CONFORMATIONS OF SURFACTANTS IN AQUEOUS SOLUTION AND CRYSTALLINE STATES

The Raman spectra were measured for sodium alkyl sulfates and potassium aliphatic carboxylates in the solid state and aqueous solutions. Vibrational assignments of Raman lines were made, and characteristic Raman lines of the alkyl sulfate ion were identified. The ethyl sulfate ion in the aqueous solution was found to exist predominantly as the trans form about the CH2–O bond. For higher alkyl sulfate ions in aqueous solutions, Raman lines due to rotational isomers with gauche CH2–CH2 bonds were observed. Longitudinal accordion frequencies of the solid state and aqueous solutions were compared in order to discuss the conformations of hydrocarbon chains in solution.

The Raman Spectra and Molecular Conformations of Surfactants in Aqueous Solution and Crystalline States

Abstract The Raman spectra were measured for sodium alkyl sulfates and potassium aliphatic carboxylates in the solid state and aqueous solutions. Vibrational assignments of Raman lines were made, and characteristic Raman lines of the alkyl sulfate ion were identified. The ethyl sulfate ion in the aqueous solution was found to exist predominantly as the trans form about the CH2–O bond. For higher alkyl sulfate ions in aqueous solutions, Raman lines due to rotational isomers with gauche CH2–CH2 bonds were observed. Longitudinal accordion frequencies of the solid state and aqueous solutions were compared in order to discuss the conformations of hydrocarbon chains in solution.

On the structure of isotropic phases in lipid-water systems

The structure of isotropic phases occurring in aqueous lipids systems are discussed on the basis of some new experimental results. Characteristic effects in the Raman spectra due to the hydrocarbon chain conformation are shown. It is proposed that the amphiphilic solution (phase L2) has a structure closely related to that of the mesophase obtained on cooling, the transition point to the liquid phase representing a loss in long-range order only. Differences in water swelling properties of this liquid phase corresponding to differences in structure according to such a phase transition mechanism are demonstrated experimentally. A simple model for the transition between spherical and cylindrical micelles in the water solution (phase L1), based on minimization of the surface-to-volume ratio, is compared with the observed transitions. The behaviour of micro-emulsions in relation to the two liquid phases L1 and L2 is discussed. Finally evidences is given for the existence of a general cubic structure type with closed water aggregates in a lipid matrix, and a model based on space-filling polyhedra is proposed.