Calorimetric studies of the effect of cis-carotenoids on the thermotropic phase behavior of phosphatidylcholine bilayers (original) (raw)
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Biochimica et Biophysica Acta (BBA) - Biomembranes, 2003
Carotenoids are the effective modulators of physical properties of model and natural membranes. To demonstrate the relationship between the structure of carotenoids and their effect on the molecular dynamics of membranes, we have investigated the influence of five structurally different carotenoids: h-carotene, lycopene, lutein, violaxanthin, zeaxanthin and additionally carotane-a fully saturated derivative of hcarotene, on thermotropic phase behaviour of dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles by means of differential scanning calorimetry (DSC). The results obtained indicate that the carotenoids used modulated the thermotropic properties of multibilayers to various extents, broadening the pretransition and the main phase transition peaks and shifting them to lower temperatures. Pronounced decrease of pretransition enthalpy (DH p) proves that carotenoids very strongly alter the membrane properties in its gel phase. Comparison of the influence of several carotenoids shows that a rigid, polyisoprenoid chain plays a basic role in altering the thermotropic properties of such membranes and the presence of rings without oxygen-containing groups has a minor significance for the observed interactions. Carotenoids containing epoxy and/or hydroxy groups attached to their rings modify the thermotropic phase behaviour of DPPC multilamellar vesicles stronger than carotenes-a result of their orientation in the DPPC bilayer.
Zeitschrift für Naturforschung C, 2002
The interaction of structurally different carotenoids with a membrane molecular model was examined by X-ray diffraction. The selected compounds were β-carotene, lycopene, lutein, violaxanthin, zeaxanthin, and additionally carotane, a fully saturated derivative of β-carotene. They present similarities and differences in their rigidity, the presence of terminal ionone rings and hydroxy and epoxy groups bound to the rings. The membrane models were multibilayers of dipalmitoylphosphatidylcholine (DPPC), chosen for this investigation because the 3 nm thickness of the hydrophobic core of its bilayer coincides with the thickness of the hydrophobic core of thylakoid membranes and the length of the carotenoid molecules. Results indicate that the six compounds induced different types and degrees of structural perturbations to DPPC bilayers in aqueous media. They were interpreted in terms of the molecular characteristics of DPPC and the carotenoids. Lycopene and violaxanthin induced the highes...
Carotenoids as modulators of lipid membrane physical properties
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2005
Carotenoids are a group of pigments present both in the plant and animal kingdoms, which play several important physiological functions. The protection against active oxygen species, realised via the quenching of excited states of photosensitising molecules, quenching of singlet oxygen and scavenging of free radicals, is one of the main biological functions of carotenoids. Several recent research indicate that the protection of biomembranes against oxidative damage can be also realised via the modification of the physical properties of the lipid phase of the membranes. This work presents an overview of research on an effect of carotenoids on the structural and dynamic properties of lipid membranes carried out with the application of different techniques such as Electron Paramagnetic Resonance, Nuclear Magnetic Resonance, Differential Scanning Calorimetry, X-ray diffractometry, monomolecular layer technique and other techniques. It appears that, in most cases, polar carotenoids span lipid bilayer and have their polar groups anchored in the opposite polar zones of the membrane. Owing to the van der Waals interactions of rigid rod-like molecules of carotenoid and acyl chains of lipids, pigment molecules rigidify the fluid phase of the membranes and limit oxygen penetration to the hydrophobic membrane core susceptible to oxidative degradation. D
Biophysical Journal, 1989
Differential scanning calorimetry (DSC) has been employed to study the effects of cholesterol on the phase transition of C(18):C(10) phosphatidylcholine (C(18):C(10)PC). C(18):C(10)PC is an asymmetric mixed-chain phosphatidylcholine known to form mixed-interdigitated structures below the transition temperature and form partially interdigitated lipid bilayers above the transition. Three types of samples were used. The treated sample is the lipid dispersion that had undergone three freezethaw cycles and stored at 40C for more than 48 h. The untreated sample was made by vortexing the dry lipid in 50 mM KCI, without the above-mentioned pretreatment. The cold-treated sample was prepared by incubating the treated sample at-20°C for 15 d. There is no apparent difference in the DSC curves between the treated and cold-treated samples. The data derived from the treated samples seem to be more repro-the present study is that cholesterol may have a function in preventing lipids from forming highly ordered interdigitated structures in natural membranes.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1999
We have studied the effects of cholesterol on the thermotropic phase behavior of aqueous dispersions of a homologous series of linear saturated phosphatidylcholines, using high-sensitivity differential scanning calorimetry and an experimental protocol which ensures that broad, low-enthalpy phase transitions are accurately monitored. We find that the incorporation of small amounts of cholesterol progressively decreases the temperature and the enthalpy, but not the cooperativity, of the pretransition of all phosphatidylcholines exhibiting such a pretransition and that the pretransition is completely abolished at cholesterol concentrations above 5 mol % in all cases. The incorporation of increasing quantities of cholesterol also alters the main or chain-melting phase transition of these phospholipid bilayers in both hydrocarbon chain length-dependent and hydrocarbon chain length-independent ways. At cholesterol concentrations of from 1 to 20-25 mol %, the DSC endotherms of all phosphatidylcholines studied consist of a superimposed sharp and broad component, the former ascribed to the melting of cholesterol-poor and the latter to the melting of the cholesterol-rich phosphatidylcholine domains. The temperature and cooperativity of the sharp component are reduced only slightly and in a chain length-independent manner with increasing cholesterol concentration, an effect we ascribe to the colligative effect of the presence of small quantities of cholesterol at the domain boundaries. Moreover, the enthalpy of the sharp component decreases and becomes zero at 20-25 mol % cholesterol for all of the phosphatidylcholines examined.(ABSTRACT TRUNCATED AT 250 WORDS)
2005
A molecular dynamics (MD) simulation of the fully hydrated bilayer made of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and containing -carotene (-Car) molecules was carried out as a complementary approach to experimental techniques to investigate the orientation of -Car in the lipid membrane as well as its influence on the bilayer properties. The bilayer reached thermal equilibrium after 1200 ps of MD simulation and the productive run was carried out for 2800 ps. The results indicate that the carotene rings are located in the region occupied by the carbonyl groups of the POPC ␥-chain with no trace of penetration towards the centre of the bilayer. Carotene exhibits an ordering effect on both the and the ␥-chain. While the fully saturated ␥-chain is affected evenly along, the order of the mono-unsaturated -chain is modified mainly below the double bond. In general, a high value of the order parameter and the chain tilt in the range from 11.4 • to 26.7 • were observed for the -Car molecules. However, for chain segment adjacent to methyl groups the value of the order parameter is low and the tilt angle is close to 75 • . Moreover, the probability of trans conformation being generally close to 1.0 along the -Car chain is reduced for these segments. Our MD simulation study suggests two pools of the preferential orientation of -Car: a slightly bent structure corresponding to a small chain tilt angle and a rather stretched structure that corresponds to a higher chain tilt. The results are discussed in the light of experimental findings.
Advances in Planar Lipid Bilayers and Liposomes, 2013
Carotenoids are the most widely spread pigments, both in the plant and animal kingdom, that perform numerous important physiological functions. In photosynthetic organisms, carotenoids are involved in the processes of light harvesting, photoprotection, and electron transfer, serve as scavengers of reactive oxygen species, and perform a structural role in photosynthetic membranes. In animals and humans, carotenoids perform a number of functions, of which the best established are their provitamin A activity and antioxidant properties. A great number of investigations devoted to understanding the basic principles of carotenoid impact on membrane organization, Advances in Planar Lipid Bilayers and Liposomes, Volume 17 # 2013 Elsevier Inc.
The effects of various peptides on the thermotropic properties of phosphatidylcholine bilayers
Biophysical Chemistry, 1984
The effects of an amino acid derivative (N-benzoyl-t_-argininamide). four small peptides (Phe-Gly-Phe-Gly. gastrin-related peptide (Trp-Met-Arg-Phe-NH,). tetragastrin (Trp-Met-Asp-Phe-NH,), pentagastrin (Boc-PAla-Trp-Mel-Asp-Phe-NHz)) and one medium-sized peptide. glucagon (29 residues). on the gel-to-liquid crystalline transition of a multilamellar suspension of dimyristoylphosphatidylcholine have been studied by means of high-sensitivity differential scanning calorimetry. At low concentradons of added soluws, Ihe temperature af which the excess apparent specific heat in the gel-to-liquid crystalline phase transition of the lipid is maximal is lowered by an amount proportional to the tom1 concentration of the peptide, with proportionality constants ranging from-0.018 K mM_' for Phe-Gly-Phe-Gly to-3.1 K mM_' for the gastrin-related peptide. The lipid mixtures involving the first two solutes listed above exhibited approximately symmetrical curves of excess apparent specific heat vs. temperature. The curves for the other solutes were asymmetric, and could be well represented as the sum of either two or three two-state curves. The asymmetry. which was especially pronounced in the cases of pentagastrin and glucagon. thus appeared to be due to the presence of components having lower and/or higher transition temperatures than that of the lipid. Pentagastrin and glucagon (R.M. Epand and J.M. Sturtevant, Biochemistry 20 (1981) 4603) have much smaller effects on the gel-to-liquid crystalline phase transition of dipalmitoylphosphatidyicholine than on that of Ihe dimyristoyl analog.
1989
The thermotropic properties of hydrated dispersions of dipalmitoylphosphatidylcholine (DPPC) containing 4-biphenylacetic acid (BPAA) or fl-cyclodextrin-4-biphenylacetic acid (BPAA-fl-Cyd) at different molar ratios, have been investigated by differential scanning calorimetry (DSC). Addition of increasing amounts of BPAA or BPAA-fl-Cyd to phospholipidic dispersions leads to a main transition peak temperature (Tin) shift towards lower temperatures with a concomitant broadening of the peak. The main transition enthalpy z~H remains almost constant increasing BPAA concentration. T m shift in the presence of BPAA, observed for DPPC dispersions, was interpreted in terms of increasing membrane "fluidity". The interaction between BPAA-fl-Cyd and DPPC liposomes depends on the fraction of BPAA exchanged from the complex with membranes and it is allowed by the amphiphatic nature of this molecule. Kinetic experiments were carried out and the diffusion rate of BPAA coming from the complex into liposomes was slower than that shown by free BPAA. The results demonstrate a possible interaction of BPAA with pospholipids in cell membranes and the potential effects of such an interaction in regulating adsorption in natural membranes modulating the fluidity.