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BBA - Biomembranes (v.1758, #5)

Editorial Board (pp. ii).

Rescue of F508del CFTR: Commentary on “F508del CFTR with two altered RXR motifs escapes from ER quality control but its channel activity is thermally sensitive�? [Biochim. Biohys. Acta Biomembranes …] by Burkhard Tümmler (pp. 563-564).

F508del CFTR with two altered RXR motifs escapes from ER quality control but its channel activity is thermally sensitive by Tamás Hegedűs; Andrei Aleksandrov; Liying Cui; Martina Gentzsch; Xiu-Bao Chang; John R. Riordan (pp. 565-572).

Most cystic fibrosis (CF) patients carry the F508del mutation in the CFTR chloride channel protein resulting in its misassembly, retention in the endoplasmic reticulum (ER), and proteasomal degradation. Therefore, characterization of the retention and attempts to rescue the mutant CFTR are a major focus of CF research. Earlier, we had shown that four arginine-framed tripeptide (AFT) signals in CFTR participate in the quality control. Now we have mutated these four AFTs in all possible combinations and found that simultaneous inactivation of two of them (R29K and R555K) is necessary and sufficient to overcome F508del CFTR retention. Immunofluorescence staining of BHK cells expressing this variant indicates that it matures and is routed to the plasma membrane. Acquisition of at least some wild-type structure was detected in the pattern of proteolytic digestion fragments. Functional activity at the cell surface was evident in chloride efflux assays. However, single channel activity of the rescued mutant measured in planar lipid bilayers diminished as temperature was increased from 30 to 37 °C. These findings support the idea that absence of Phe 508 causes not only a kinetic folding defect but also steady-state structural instability. Therefore effective molecular therapies developed to alleviate disease caused by F508del and probably other misprocessing mutants will require overcoming both their kinetic and steady-state impacts.

Keywords: CFTR; Arg-based retention signal; ER exit; Membrane protein assembly; Thermal instability

The effect of calcium on the properties of charged phospholipid bilayers by Ulf R. Pedersen; Chad Leidy; Peter Westh; Günther H. Peters (pp. 573-582).

We have performed molecular dynamics simulations to investigate the structure and dynamics of charged bilayers as well as the distribution of counterions at the bilayer interface. For this, we have considered the negatively charged di-myristoyl-phosphatidyl-glycerol (DMPG) and di-myristoyl-phosphatidyl-serine (DMPS) bilayers as well as a protonated di-myristoyl-phosphatidyl-serine (DMPSH) bilayer. We were particularly interested in calcium ions due to their important role in biological systems. Simulations performed in the presence of calcium ions (DMPG, DMPS) or sodium ions (DMPS) were run for 45–60 ns. Simulation results for DMPG are compared with fluorescence measurements. The average areas per molecule were 47.4±0.5 Å² (DMPG with calcium), 47.3±0.5 Å² (DMPS with calcium), 51.3±1.0 Å² (DMPS with sodium) and 45.3±0.5 Å² (DMPSH). The structure of the negatively charged lipids is significantly affected by the counterions, where calcium ions have a more pronounced effect than sodium ions. Calcium ions were found to be tightly bound to the anionic groups of the lipid molecules and as such appear to constitute an integral part of the membrane interface on nanoseconds time scales. In contrast to sodium ions, calcium ions are localised in a narrow (∼10 Å) band around the phosphate group. The interaction of calcium with the lipid molecules enhances the molecular packing of the PG and PS lipids. This observation is in good agreement with emission spectra of the membrane partitioning probe Laurdan in DMPG multilamellar vesicles that indicate an increase in the ordering of the DMPG bilayer due to the presence of calcium. Our results indicate that calcium ions, which often function as a second messengers in living cells have a pronounced effect on membrane structures, which may have implications during signal transduction events.

Keywords: Molecular dynamics simulation; Fluorescence spectroscopy; DMPG; DMPS; Lipid order; Ion distribution; Membranes

Photosensitization of skin fibroblasts and HeLa cells by three chlorin derivatives: Role of chemical structure and delivery vehicle by Fernando Postigo; M. Luisa Sagristá; M. Africa De Madariaga; Santi Nonell; Margarita Mora (pp. 583-596).

The chemical nature of the sensitizer and its selective uptake by malignant cells are decisive to choose an appropriate biocompatible carrier, able to preserve the photosensitizing characteristics of the dye. In this paper we demonstrate the photodynamic properties of three chlorins, derived from chlorophyll a, and the usefulness of liposomal carriers to design pharmaceutical formulations. The chlorins have been quantitatively incorporated into stable liposomes obtained from a mixture ofl-α-palmitoyloleoylphosphatidylcholine andl-α-dioleoylphosphatidylserine in a 13.5:1.5 molar ratio (POPC/OOPS-liposomes). The chlorin uptake by skin fibroblasts increases steadily, reaching in all cases a plateau level dependent on both the chlorin structure and the vehicle employed. The photophysical properties of the three chlorins in THF are nearly identical and fulfill the requirements for a PDT photosensitizer. Incorporation of chlorins into liposomes induces important changes in their photophysics, but does not impair their cellular uptake or their cell photosensitization ability. In fact we observe in the cells the same photophysical behavior as in THF solution. Specifically, we demonstrate, by recording the near-IR phosphorescence of¹O₂, that the chlorins are able to photosensitize the production of¹O₂ in the cell membrane. The cell-photosensitization efficiency depended on the chlorin and cell line nature, the carrier, and the length of pre-incubation and post-irradiation periods. The high photodynamic activity of chlorin-loaded liposomes and the possibility to design liposomal carriers to achieve a specific target site favors this approach to obtain an eventual pharmaceutical formulation.

Keywords: Abbreviations; CHL-1, 3-Phorbinepropanol; 9,14-diethyl-4,8,13,18-tetramethyl-20-(3S-trans); CHL-2, 3-Phorbinepropanoic acid; 9,14-diethyl-4,8,13,18-tetramethyl-20-(3S-trans) (; meso; -pyropheophorbide; a; ); CHL-3, 3-Methyl-phorbinepropanoate; 9,14-diethyl-4,8,13,18-tetramethyl-20-(3S-trans) (; meso; -pyropheophorbide; a; methyl ester); DMEM; Dulbecco's Modified Eagle's Medium; DMPC; l; -α-dimiristoylphospatidylcholine; DPPC; l; -α-dipalmitoylphosphatidylcholine; DMSO; dimethylsulfoxide; MB; methylene blue; MTT; 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyltetrazolium bromide; OOPS; l; -α-dioleoylphosphatidylserine; PBS; Phosphate Buffered Saline; POPC; l; -α-palmitoleoylphospathidylcholine; THF; tetrahydrofuran; TPP; 5,10,15,20-tetraphenyl-21; H; ,23; H; -porphine; TPPS; 5,10,15,20-tetrakis(4-sulfonato)phenyl-21; H; ,23; H; -porphinePhotosensitizers; Fluorescence lifetime; Photocytotoxicity; Singlet oxygen; Fibroblasts; HeLa cells

Comparison between low-level 50 Hz and 900 MHz electromagnetic stimulation on single channel ionic currents and on firing frequency in dorsal root ganglion isolated neurons by I. Marchionni; A. Paffi; M. Pellegrino; M. Liberti; F. Apollonio; R. Abeti; F. Fontana; G. D'Inzeo; M. Mazzanti (pp. 597-605).

Alteration of membrane surface charges represents one of the most interesting effects of the electromagnetic exposure on biological structures. Some evidence exists in the case of extremely low frequency whereas the same effect in the radiofrequency range has not been detected. Changes in transmembrane voltages are probably responsible for the mobilization of intracellular calcium described in some previous studies but not confirmed in others. These controversial results may be due to the cell type under examination and/or to the permeability properties of the membranes. According to such a hypothesis, calcium oscillations would be a secondary effect due to the induced change in the membrane voltage and thus dependent on the characteristics of ionic channels present in a particular preparation. Calcium increases could suggest more than one mechanism to explain the biological effects of exposure due to the fact that all the cellular pathways using calcium ions as a second messenger could be, in theory, disturbed by the electromagnetic field exposure. In the present work, we investigate the early phase of the signal transmission in the peripheral nervous system. We present evidence that the firing rate of rat sensory neurons can be modified by 50/60 Hz magnetic field but not by low level 900 MHz fields. The action of the 50/60 Hz magnetic field is biphasic. At first, the number of action potentials increases in time. Following this early phase, the firing rate decreases more rapidly than in control conditions. The explanation can be found at the single-channel level. Dynamic action current recordings in dorsal root ganglion neurons acutely exposed to the electromagnetic field show increased functionality of calcium channels. In parallel, a calcium-activated potassium channel is able to increase its mean open time.

Keywords: Electromagnetic field (EMF); Extremely low frequency (ELF); Radiofrequency (RF); Dorsal root ganglion (DRG); Ca and K single channel; Firing rate

Delivery of substances and their target-specific topical activation by Rüdiger Pipkorn; Waldemar Waldeck; Herbert Spring; Jürgen W. Jenne; Klaus Braun (pp. 606-610).

Goal in pharmaceutical research is achievement of necessary drug concentrations in the target organ, effective treatment with safe delivery of genetic agents, while sparing normal tissue and minimizing side effects. A new “BioShuttle�?-delivery system harbouring a cathepsin B cutting site, a nuclear address sequence and a functional peptide was developed and tumor cells were treated. Transport and subcellular activation were determined by confocal laser scanning microscopy permitting the conclusion: BioShuttle-conjugates prove as efficient tools for genetic interventions by selective and topical activation of therapeutic peptide precursors by enzymatic cleavage. As shown here for glioma cells and the cathepsin B cleavable site, living cells can be treated with high specificity and selectivity for diagnostic and therapeutic purposes.

Keywords: Cathepsin B; Drug targeting; Glioblastoma multiforme; Intracellular targeting; Solid phase peptide synthesis; SPPS; Transmembrane transport

Band 3 tyr-phosphorylation in human erythrocytes from non-pregnant and pregnant women by Luciana Bordin; Silvia Quartesan; Francesco Zen; Fabio Vianello; Giulio Clari (pp. 611-619).

Pregnancy is associated with changes in circulating red blood cells, mainly involving band 3 protein and membrane lipid peroxidation. Membrane band 3 is a multifunctional protein containing four Tyr-phosphorylatable residues which modulate the physiological status of erythrocytes by regulating glycolysis, cell shape and membrane transport. Erythrocytes from nine pregnant and 12 age-matched non-pregnant healthy women were subjected to oxidative and hyperosmotic stress conditions and the extent of band 3 Tyr-phosphorylation and membrane Syk recruitment as a membrane marker were evaluated. Results indicated that, in pregnancy, red blood cells show a decrease in band 3 Tyr-phosphorylation and a clear-cut rearrangement of band 3 protein within the membrane. In fact, band 3 shows a decrease in high molecular weight aggregates (HMWA), with different subdivision between Triton-soluble and -insoluble compartments, and an increase in proteolytic fragments. In conclusion, it is demonstrated that pregnancy is associated with membrane adjustments which reduce the sensitivity of erythrocytes to both oxidative and osmotic stress. Band 3 Tyr-phosphorylation is proposed as a new parameter in the evaluation of erythrocyte membrane arrangement.

Keywords: Human erythrocytes in pregnancy; Band 3 Tyr-phosphorylation; Oxidative stress; Osmotic stress; Band 3 electrophoretic pattern

Interactions between model membranes and lignin-related compounds studied by immobilized liposome chromatography by Elisabet Boija; Gunnar Johansson (pp. 620-626).

In order to elucidate the modes of interaction between lignin precursors and membranes, we have studied the influence of temperature, lipid composition and buffer composition on the partitioning of monolignol and dilignol model substances into phospholipid bilayers. The partitioning was determined by immobilized liposome chromatography, which is an established method for studies of pharmaceutical drugs but a new approach in studies of lignin synthesis. The temperature dependence of the retention and the effect of a high ammonium sulfate concentration in the mobile phase demonstrated that the interaction involved both hydrophobic effects and polar interactions. There was also a good correlation between the partitioning and the estimated hydrophobicity, in terms of octanol/water partitioning. The partitioning behavior of the model substances suggests that passive diffusion over the cell membrane is a possible transport route for lignin precursors. This conclusion is strengthened by comparison of the present results with the partitioning of pharmaceutical drugs that are known to pass cell membranes by diffusion.

Keywords: Abbreviations; PC; phosphatidylcholine; ILC; immobilized liposome chromatography; PS; phosphatidylserine; DSTAP; 1,2-distearoyl-3-methylammoniumpropane; VG; veratryl glycol; MSA; α-methylsyringyl alcohol; TMBA; 3,4,5-trimethoxybenzyl alcohol; ADMPA; 4-acetyl-2,6-dimethoxyphenyl acetate; APA; 4-acetoxy-3,5-dimethoxy-α-(2,6-dimethoxyphenoxy) acetophenone; APH; 4′-hydroxy-3′,5′-dimethoxy-2-(o-methoxyphenoxy) acetophenone; HMPA; 1-(4-hydroxy-3-methoxyphenyl)-2-(2,6-dimethoxyphenoxy) acetophenone; PP; 3-hydroxy-3′,4′-dimethoxy-2-(o-methoxyphenoxy) propiophenoneImmobilized-liposome chromatography; Lignin; Liposomes; Monolignol; Octanol/water partitioning; Phospholipid bilayers

Functional involvement of membrane-embedded and conserved acidic residues in the ShaA subunit of the multigene-encoded Na⁺/H⁺ antiporter in Bacillus subtilis by Saori Kosono; Yusuke Kajiyama; Shin Kawasaki; Toko Yoshinaka; Koki Haga; Toshiaki Kudo (pp. 627-635).

ShaA, a member of a multigene-encoded Na⁺/H⁺ antiporter in B. subtilis, is a large integral membrane protein consisting of 20 transmembrane helices (TM). Conservation of ShaA-like protein subunits in several cation-coupled enzymes, including the NuoL (ND5) subunit of the H⁺-translocating complex I, suggests the involvement of ShaA in cation transport. Bacillus subtilis ShaA contains six acidic residues that are conserved in ShaA homologues and are located in putative transmembrane helices. We examined the functional involvement of the six transmembrane acidic residues of ShaA by site-directed mutagenesis. Mutation in glutamate (Glu)-113 in TM-4, Glu-657 in TM-18, aspartate (Asp)-734 and Glu-747 in TM-20 abolished the antiport activity, suggesting that these residues play important roles in the ion transport of Sha. The acidic group was necessary and sufficient in Glu-657 and Asp-743, while it was not true of Glu-113 and Glu-747. Mutation in Asp-103 in TM-3, which is conserved in ShaA-types but not in ShaAB-types, partially affected on the antiport activity. Mutation in Asp-50 in TM-2 resulted in a unexpected phenotype: mutants retained the wild type level of ability to confer NaCl resistance to the Na⁺/H⁺ antiporter-deficient E. coli KNabc, but showed a very low antiport activity. The acidic group of Asp-50 and Asp-103 was not essential for the function. Our results suggested that these acidic residues are functionally involved in the ion transport of Sha, and some of them probably in cation binding and/or translocation.

Keywords: A multigene-encoded Na; ⁺; /H; ⁺; antiporter; NuoL; Transmembrane topology; Conserved acidic residues; Site-directed mutagenesis:; Bacillus subtilis

Preparation and characterization of a stratum corneum substitute for in vitro percutaneous penetration studies by Miranda de Jager; Wouter Groenink; Joop van der Spek; Co Janmaat; Gert Gooris; Maria Ponec; Joke Bouwstra (pp. 636-644).

The intercellular stratum corneum (SC) lipids form the main barrier for diffusion of substances through the skin. A porous substrate covered with synthetic SC lipids would be an attractive model to study percutaneous penetration, hereby replacing native human SC. Prerequisite is that this stratum corneum substitute (SCS) is prepared with a uniform lipid composition and layer thickness. Furthermore, the lipid organization and orientation should resemble that in SC. The objective of this study was to investigate the utility of an airbrush spraying device to prepare a SCS composed of cholesterol, ceramides and free fatty acids on a polycarbonate filter. The results demonstrate that a proper choice of solvent mixture and lipid concentration is crucial to achieve a uniform distribution of the applied lipids over the filter surface. A smooth and tightly packed lipid layer is only obtained when the equilibration conditions are appropriately chosen. The SCS possesses two crystalline lamellar phases with periodicities similar to those present in native SC. The orientation of these lamellae is mainly parallel to the surface of the polycarbonate filter, which resembles the orientation of the intercellular SC lipids. In conclusion, the airbrush technique enables generation of a homogeneous SCS, which ultimately may function as a predictive in vitro percutaneous penetration model.

Keywords: Skin; Permeability; Diffusion; Ceramide; X-ray diffraction

Phospholipid requirement and pH optimum for the in vitro enzymatic activity of the E. coli P-type ATPase ZntA by Jochen Zimmer; Declan A. Doyle (pp. 645-652).

Detergent solubilization and purification of the E. coli heavy metal P-type ATPase ZntA yields an enzyme with reduced hydrolytic activity in vitro. Here, it is shown that the in vitro hydrolytic activity of detergent solubilized ZntA is increased in the presence of negatively charged phospholipids and at slightly acidic pH. The protein–lipid interaction of ZntA was characterized by enzyme-coupled ATPase assays and fluorescence spectroscopy. Among the most abundant naturally occurring phospholipids, only phosphatidyl-glycerol lipids (PG) enhance the in vitro enzymatic ATPase activity of ZntA. Re-lipidation of detergent purified ZntA with 1,2-dioleoylphosphatidyl-glycerol (DOPG) increases the ATPase activity four-fold compared to the purified state. All other E. coli phospholipids fail to activate the ATPase. Among the phosphatidyl-glycerol family, highest activity was observed for 1,2-dioleoyl-PG followed by 1,2-dimyristoyl-PG, 1,2-dipalmitoyl-PG and 1,2-distearoyl-PG. Increasing intrinsic Trp fluorescence quantum yield upon relipidation of ZntA was used to determine a pH maximum for lipid binding at pH 6.7. The pH dependence of the lipid binding was confirmed by pH-dependent ATPase assays showing maximum activity at pH 6.7. The biophysical characterization of detergent solubilized membrane proteins crucially relies on the conformational stability and functional integrity of the protein under investigation. The present study describes how the E. coli ZntA P-type ATPase can be stabilized and functionally activated in a detergent solubilized system.

Keywords: Abbreviations; a.u.; arbitrary units; C12E8; dodecyl octaethylene glycol monoether; DTT; dithiothreitol; HEPES; N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid; MES; 2-(morpholino)-ethanesulfonic acid; MRC; Medical Research Council, Trishydroxymethyl-aminomethaneATPase assay; Lipid activation; P-type ATPase; pH optimum

Desolvation map of the i-face of phospholipase A2 by Yu-Cheng Tsai; Bao-Zhu Yu; Yu-Zhen Wang; Junghuei Chen; Mahendra K. Jain (pp. 653-665).

The changes in the microenvironment of the Trp-3 on the i-face of pig pancreatic IB phospholipase A₂ (PLA2) provide a measure of the tight contact (Ramirez and Jain, Protein Sci. 9, 229–239, 1991) with the substrate interface during the processive interfacial turnover. Spectral changes from the single Trp-substituent at position 1, 2, 6, 10, 19, 20, 31, 53, 56 or 87 on the surface of W3F PLA2 are used to probe the Trp-environment. Based on our current understanding only the residue 87 is away from i-face, therefore all other mutants are well suited to report modest differences along the i-face. All Trp-mutants bind tightly to anionic vesicles. Only those with Trp at 1, 2 or 3 near the rim of the active site on the i-face cause significant perturbation of the catalytic functions. Most other Trp-mutants showed < 3-fold change in the interfacial processive turnover rate and the competitive inhibition by MJ33. Binding of calcium to the enzyme in the aqueous phase had modest effect on the Trp-emission intensity. However, on the binding of the enzyme to the interface the fluorescence change is large, and the rate of oxidation of the Trp-substituent with N-bromosuccinimide depends on the location of the Trp-substituent. These results show that the solvation environment of the Trp-substituents on the i-face is shielded in the enzyme bound to the interface. Additional changes are noticeable if the active site of the bound enzyme is also occupied, however, the catalytically inert zymogen of PLA2 (proPLA2) does not show such changes. Significance of these results in relation to the changes in the solvent accessibility and desolvation of the i-face of PLA2 at the interface is discussed.

Keywords: Abbreviations; DC; ₇; PC; 1,2-Diheptanoyl-; sn; -3-glycerophocholine; DMPM; 1,2-dimyristoyl-; sn; -3-glycerophosphomethanol; DTPM; 1,2-ditetradecyl-; rac; -3-glycerophosphomethanol; DTSO; ₄; 1,2-ditetradecyl-; rac; -3-glycero-sulfate; i-face; the interface binding surface of PLA2; MJ33; 1-hexadecyl-3-trifluoroethyl-; rac; -glycero-2-phosphomethanol; NBS; N-bromosuccinimide; octyl-Trp; octylester of tryptophan; PLA2; IB phospholipase A2 from pig pancreas; RET; fluorescence resonance energy transferredInterfacial kinetics; Processive turnover; I-face; Lipid-protein interaction; Phospholipase A; ₂

Regulation of the mechanosensitive cation channels by ATP and cAMP in leech neurons by Cristina Barsanti; Monica Pellegrini; Mario Pellegrino (pp. 666-672).

Single-channel recordings were used to study the modulation of stretch-activated channels (SACs) by intracellular adenosine nucleotides in identified leech neurons. These channels exhibited two activity modes, spike-like (SL) and multiconductance (MC), displaying different polymodal activation. In the absence of mechanical stimulation, internal perfusion of excised patches with ATP induced robust and reversible activation of the MC but not of the SL mode. The ATP effect on channel activity was dose-dependent within a range of 1 μM–1 mM and was induced at different values of intracellular pH and Ca²⁺. The non-hydrolyzable ATP analog AMP-PNP, ATP without Mg²⁺ or ADP also effectively enhanced MC activity. Adenosine mimicked the effect of its nucleotides. At negative membrane potentials, both ATP and adenosine activated the channel. Moreover, ATP but not adenosine induced a flickering block. Addition of cAMP during maximal ATP activation completely and reversibly inhibited the channel, with activation and deactivation times of minutes. However, cAMP alone only induced a weak and rapid channel activation, without inhibitory effects. The expression of these channels in the growth cones of leech neurons, their permeability to Ca²⁺ and their sensitivity to intracellular cAMP are consistent with a role in the Ca²⁺ oscillations associated with cell growth.

Keywords: Mechanosensitive ion channel; Patch-clamp; Single-channel recording; TRP channel; Modulation; Purine

Two-component bacterial multidrug transporter, EbrAB: Mutations making each component solely functional by Takashi Kikukawa; Toshifumi Nara; Tsunehisa Araiso; Seiji Miyauchi; Naoki Kamo (pp. 673-679).

EbrAB in Bacillus subtilis belongs to a novel small multidrug resistance (SMR) family of multidrug efflux pumps. EmrE in Escherichia coli, a representative of SMR, functions as a homo-oligomer in the membrane. On the other hand, EbrAB requires a hetero-oligomeric configuration consisting of two polypeptides, EbrA and EbrB. Although both polypeptides have a high sequence similarity, expression of either single polypeptide does not confer the multidrug-resistance. We performed mutation studies on EbrA and B to determine why EbrAB requires the hetero-oligomerization. Mutants of EbrA and B lacking both the hydrophilic loops and the C-terminus regions conferred the multidrug-resistance solely by each protein. This suggests that the hydrophilic loops and the C-terminus regions constrain them to their respective conformations upon the formation of the functional hetero-oligomer.

Keywords: EbrAB; EmrE; Smr; Ion-coupled transporter; Multidrug resistance

Monosaccharide composition, chain length and linkage type influence the interactions of oligosaccharides with dry phosphatidylcholine membranes by Constança Cacela; Dirk K. Hincha (pp. 680-691).

Sugars play an important role in the desiccation tolerance of most anhydrobiotic organisms and disaccharides have been extensively investigated for their ability to stabilize model membranes in the dry state. Much less is known about the ability of oligosaccharides to protect dry membranes. However, it has been shown that different structural families of oligosaccharides have different efficacies to interact with and protect membranes during drying. Here, we have compared three families of linear oligosaccharides (fructans, malto-oligosaccharides, manno-oligosaccharides) for their chain-length dependent lyoprotective effect on egg phosphatidylcholine liposomes. We found increased protection with chain length for the fructans, a moderate decrease in protection with chain length for malto-oligosaccharides, and a strong decrease for manno-oligosaccharides. Using Fourier-transform infrared spectroscopy and differential scanning calorimetry, we show that the degree of lyoprotection of the different sugars is closely related to their influence on the gel to liquid–crystalline phase behavior of the dry membranes and to the extent of H-bonding to different groups (CO, PO, choline) in the lipids. Possible structural characteristics of the different oligosaccharides that may determine the extent to which they are able to interact with and protect membranes are discussed.

Keywords: Desiccation; Fourier-transform infrared spectroscopy; Lipid phase transitions; Liposomes; Oligosaccharides; Sugar–membrane interactions

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BBA - Biomembranes (v.1758, #5)