Modifications of lipid structure and their influence on mesomorphism in model membranes: the influence of hydrocarbon chains

1986 ◽  
Vol 64 (1) ◽  
pp. 44-49 ◽  
Author(s):  
K. M. W. Keough
Keyword(s):  
Liquid Crystalline ◽  
Analytical Data ◽  
Model Membranes ◽  
Positional Isomers ◽  
Double Bonds ◽  
Enthalpy Changes ◽  
Hydrocarbon Chains ◽  
Acyl Chains ◽  
Crystalline Phase Transition ◽  
Subsequent Introduction

The influence of hydrocarbon chains on the temperature (TG–LC) of the gel to liquid-crystalline phase transition of model membranes has been investigated over an extensive variety of phosphatidylcholines (PC). The TG–LC is dependent upon the length of the hydrocarbon chains, on whether or not the chains are saturated or have been modified in some way, and on the position of any modification along the chain. For PC having two different acyl chains (heteroacid PC) in the sn-1 and sn-2 positions, the TG–LC is dependent on the chain position and on the inequivalence of chain penetration into the bilayer. Positional isomers of PC have different TG–LC. The first two double bonds introduced in each chain of a PC cause a much greater reduction in TG–LC and in the enthalpy change of the transition than does the subsequent introduction of additional double bonds. Dipolyunsaturated PC have uncooperative (broad) transitions that occur at low temperatures and have small enthalpy changes. While each PC has unique transitional characteristics, there are a number of patterns in the TG–LC which emerge on consideration of all the available data. One such pattern may be useful in predicting TG–LC from analytical data on the composition and positions of acyl chains of various lipids.

Temperature-induced changes in lecithin model membranes detected by novel covalent spin-labelled phospholipids

1977 ◽  
Vol 55 (2) ◽  
pp. 173-185 ◽  
Author(s):  
L. Stuhne-Sekalec ◽  
N. Z. Stanacev
Keyword(s):  
Transition Temperature ◽  
Fatty Acyl ◽  
Model Membranes ◽  
Head Group ◽  
Polar Head Group ◽  
Polar Group ◽  
Conformational Isomers ◽  
Hydrocarbon Chains ◽  
Acyl Chains ◽  
Induced Changes

Several spin-labelled phospholipids carrying covalently bound 5-doxylstearic acid (2-(3-carboxydecyl)-2-hexyl-4,4-dimethyl-3-oxazolidinoxyl) were intercalated in liposomes of saturated and unsaturated lecithins. Temperature-induced changes of these liposomes, detected by the spin-labelled phospholipids, were found to be in agreement with the previously described transitions of hydrocarbon chains of host lecithins detected by different probes and different techniques, establishing that spin-labelled phosopholipids are sensitive probes for the detection of temperature-induced changes in lecithin model membranes. In addition to the detection of already-known transitions in lecithin liposomes, the coexistence of two distinctly different environments was observed above the characteristic transition temperature. This phenomenon was tentatively attributed to the influence of the lecithin polar group on the fluidity of fatty acyl chains near the polar group. Combined with other results from the literature, the coexistence of two environments could be associated with the coexistence of two conformational isomers of lecithin, differing in the orientation of the polar head group with respect to the plane of bilayer. These findings have been discussed in view of the present state of knowledge regarding temperature-induced changes in model membranes.

Temperature Dependence of the Phospholipids Bilayers Stability, Studied by FTIR Spectroscopy

2008 ◽  
Vol 59 (3) ◽  
pp. 356-359 ◽  
Author(s):  
Feride Severcan ◽  
Catalin Agheorghiesei ◽  
Dana-Ortansa Dorohoi
Keyword(s):  
Phase Transition ◽  
Lipid Bilayers ◽  
Liquid Crystalline ◽  
Correlation Spectroscopy ◽  
Liquid Crystalline Phases ◽  
Hydrocarbon Chains ◽  
Acyl Chains ◽  
Stretching Vibrations ◽  
Two Phases ◽  
Spectral Ranges

The temperature induced modifications in the lipid bilayers in water were studied by using 2D-FTIR Correlation Spectroscopy. The spectral range analysed in this paper corresponds to symmetric and asymmetric stretching vibrations of the �CH2 groups from the acyl chains of DPPC. Autocorrelation peaks at 2916 cm-1 and 2848.5 cm-1 and asynchrone modifications in the spectral ranges 2916-3000 cm-1 and 2848-3000 cm-1 were evidenced. The revealed modifications indicate changes in the conformers of the hydrocarbon chains in the phase transition from the gel to liquid crystalline phases, as well as the variations in the concentration of the two phases with temperature increasing.

scholarly journals Interactions of Linear Analogues of Battacin with Negatively Charged Lipid Membranes

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 192
Author(s):  
Kinga Burdach ◽  
Dagmara Tymecka ◽  
Aneta Urban ◽  
Robert Lasek ◽  
Dariusz Bartosik ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Liquid Crystalline ◽  
Lipid Membrane ◽  
Attenuated Total Reflection ◽  
Gram Positive ◽  
Insertion Depth ◽  
Force Microscopy ◽  
Acyl Chains ◽  
Hydrophobic Portion ◽  
Membrane Fluidization

The increasing resistance of bacteria to available antibiotics has stimulated the search for new antimicrobial compounds with less specific mechanisms of action. These include the ability to disrupt the structure of the cell membrane, which in turn leads to its damage. In this context, amphiphilic lipopeptides belong to the class of the compounds which may fulfill this requirement. In this paper, we describe two linear analogues of battacin with modified acyl chains to tune the balance between the hydrophilic and hydrophobic portion of lipopeptides. We demonstrate that both compounds display antimicrobial activity with the lowest values of minimum inhibitory concentrations found for Gram-positive pathogens. Therefore, their mechanism of action was evaluated on a molecular level using model lipid films mimicking the membrane of Gram-positive bacteria. The surface pressure measurements revealed that both lipopeptides show ability to bind and incorporate into the lipid monolayers, resulting in decreased ordering of lipids and membrane fluidization. Atomic force microscopy (AFM) imaging demonstrated that the exposure of the model bilayers to lipopeptides leads to a transition from the ordered gel phase to disordered liquid crystalline phase. This observation was confirmed by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) results, which revealed that lipopeptide action causes a substantial increase in the average tilt angle of lipid acyl chains with respect to the surface normal to compensate for lipopeptide insertion into the membrane. Moreover, the peptide moieties in both molecules do not adopt any well-defined secondary structure upon binding with the lipid membrane. It was also observed that a small difference in the structure of a lipophilic chain, altering the balance between hydrophobic and hydrophilic portion of the molecules, results in different insertion depth of the active compounds.

Structures and properties of mixtures of branched chain compounds and lecithin: phytol, α-tocopherol (vitamin E), and phytanic acid

1979 ◽  
Vol 57 (4) ◽  
pp. 458-465 ◽  
Author(s):  
Robert J. Cushley ◽  
Bruce J. Forrest ◽  
Anne Gillis ◽  
Jenifer Tribe
Keyword(s):  
Differential Scanning Calorimetry ◽  
Vitamin E ◽  
Phytanic Acid ◽  
Liquid Crystalline ◽  
Egg Yolk ◽  
Scanning Calorimetry ◽  
Chain Molecules ◽  
Structures And Properties ◽  
Branched Chain ◽  
Crystalline Phase Transition

Phospholipid bilayers containing branched chain molecules, phytol (1), vitamin E (2), and phytanic acid (3), have been investigated by 31P nmr, esr, and differential scanning calorimetry (dsc).A 31P lanthanide induced shift study indicated varying permeabilities to Pr3+ in the order phytanic acid > vitamin E > phytol > egg yolk lecithin alone; the half-lives (in days) were 0.002, 0.14, 0.83, and 6.5, respectively. The activation energy for Pr3+ permeation through the egg yolk lecithin–phytol membrane was found to be 84.9 ± 0.8 kJ.The following esr order parameters, S3, were obtained using the extrinsic spin label, 5-doxylpalmitic acid, in oriented mixed multibilayers: S3 (1) = 0.29, S3 (2) = 0.50, and S3 (3) = 0.02.Differential scanning calorimetry revealed a lowering of the gel–liquid crystalline phase transition temperature, Tc, as the concentration of incorporated isoprenoid compound increases, with eventual disappearance of the endotherm. Specific entropy, s, calculated for dipalmitoyl lecithin +25 mol% 3 is 126 J kg−1 K−1 compared to s = 114.2 J kg−1 K−1 for 1and s = 85 J kg−1 K−1 for 2.

Structural Homogeneity in Unsaturated Fatty Acids of Marine Lipids. A Review

1964 ◽  
Vol 21 (2) ◽  
pp. 247-254 ◽  
Author(s):  
R. G. Ackman
Keyword(s):  
Fatty Acids ◽  
Double Bond ◽  
Polyunsaturated Fatty Acids ◽  
Chain Length ◽  
Unsaturated Fatty Acids ◽  
Analytical Data ◽  
Double Bonds ◽  
Marine Origin ◽  
Methyl Group ◽  
Marine Lipids

Consideration of recent analytical data supports the conclusion that the longer-chain polyunsaturated fatty acids of marine origin are all structurally homogeneous in that the double bonds are cis, the double bonds methylene interrupted, and that, with the exception of the C16 chain length, the ultimate double bond will normally be three, six or nine carbon atoms removed from the terminal methyl group.

scholarly journals Increased fatty acyl saturation of phosphatidylinositol phosphates in prostate cancer progression

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Atsushi Koizumi ◽  
Shintaro Narita ◽  
Hiroki Nakanishi ◽  
Masaki Ishikawa ◽  
Satoshi Eguchi ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Progression ◽  
Fatty Acyl ◽  
Human Prostate ◽  
Pathological Stage ◽  
Double Bonds ◽  
Prostate Hyperplasia ◽  
Cellular Processes ◽  
Acyl Chains ◽  
Phosphatidylinositol Phosphates

Abstract Phosphoinositides (PIPs) participate in many cellular processes, including cancer progression; however, the metabolic features of PIPs associated with prostate cancer (PCa) are unknown. We investigated PIPs profiles in PTEN-deficient prostate cancer cell lines, human prostate tissues obtained from patients with PCa and benign prostate hyperplasia (BPH) specimens using mass spectrometry. In immortalized normal human prostate PNT1B cells, PTEN deficiency increased phosphatidylinositol tris-phosphate (PIP3) and decreased phosphatidylinositol mono- and bis-phosphate (PIP1 and PIP2), consistent with PTEN’s functional role as a PI(3,4,5)P3 3-phosphatase. In human prostate tissues, levels of total (sum of all acyl variants) phosphatidylinositol (PI) and PIP1 in PCa were significantly higher than in BPH, whereas PIP2 and PIP3 contents were significantly lower than in BPH. PCa patients had significantly higher proportion of PI, PIP1, and PIP2 with 0–2 double bonds in acyl chains than BPH patients. In subgroup analyses based on PCa aggressiveness, mean total levels of PI with 0–2 double bonds in acyl chains were significantly higher in patients with pathological stage T3 than in those with pathological stage T2. These data indicate that alteration of PIPs level and the saturation of acyl chains may be associated with the development and aggressiveness of prostate cancer, although it is unknown whether this alteration is causative.

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