Synthesis and characterization of N-octanoyl-beta-D-glucosylamine, a new surfactant for membrane studies

The new nonionic glycosidic surfactant N-octanoyl-beta-D-glucosylamine (NOGA, molar mass 305.37 g) was synthesized through an easy and efficient two-step procedure. Specifically, beta-D-glucosylamine was obtained by the replacement of the anomeric hydroxyl of D-glucose by an amino group which was then selectively acylated. NOGA was finally purified by silica gel column chromatography and recrystallization. This compound is stable and soluble in water and usual buffers up to 80 mM at 4 degrees C and up to 0.2 M at 37 degrees C. NOGA solutions are also characterized by a low ultraviolet light absorbance above 250 nm (epsilon 280 approximately 1.5 M-1 cm-1). Due to its very high critical micelle concentration (CMC = 80 mM, as determined by spectrofluorimetry), this surfactant may easily be removed from samples by dialysis or, to a lesser extent, by adsorption onto hydrophobic beads. Furthermore, NOGA is colorimetrically titrable by the ninhydrin method and its weak interference in protein determination by the bicinchoninic acid method is easy to overcome. This surfactant exhibits a good solubilizing power toward membrane proteins, with a marked selectivity for spiralin, a bacterial surface antigen. Protein extraction started below the CMC, but was much more effective above this concentration threshold. NADH oxidase activity, ligand binding by the glycine betaine-binding protein, and antigenicity of more than 20 membrane or soluble proteins were not altered by NOGA. Thus, owing to its extraction efficacy and mildness toward protein structure and activity, NOGA should prove useful for membrane studies and offers the additional advantage of being easy to synthesize at low cost.

[Synthesis of new antirusty disinfectants. I]

New quaternary ammonium salts [N-alkyl-N-2-hydroxyethyl-N,N-dimethylammonium ethyl phosphate (21, 22), isopropyl phosphate (23), n-butyl phosphate (24) and N-alkyl-N-2-hydroxy-3-phenoxypropyl-N,N-dimethylammonium ethyl phosphate (25, 26), isopropyl phosphate (27), n-butyl phosphate (28) and bis(N-alkyl-N-2-hydroxy-3-phenoxypropyl-N,N-dimethylammonium) malate (29), fumarate (30), succinate (31), adipate (32) and N-alkyl-N-2-hydroxy-3-phenoxypropyl-N,N-dimethylammonium tartrate (33)] were synthesized by alkylation of the corresponding trialkylammonium salts with various epoxy compounds. The new quaternary ammonium salts showed much greater bactericidal activities and antirusting effects than those of benzalkonium chloride. They had also good compatibilities since no precipitate was observed if the solution of any anionic surface active agents were added to the solution of these new quaternary ammonium salts. This property is the same as that of amphoteric surface active agents.

Design, synthesis and structure of an amphipathic peptide with pH-inducible haemolytic activity

A synthetic, 26-residue peptide having a strong helix forming potential in the protonated state was designed to interact with lipid bilayers in a pH-dependent way. On the basis of this concept a cluster of four glutamic acid residues was inserted in the central region of the amphipathic peptide to promote helix destabilization by mutual charge repulsion at neutral pH. Protonation of these residues might then bring about both a pH-mediated change in hydrophobicity and conformation forming a membrane-active amphiphilic helix. The sequence GLGTLLTLLEFLLEELLEFLKRKRQQamide produced by the design strategy induced pH-triggered lysis of human erythrocytes. A molecular model correlating the lytic activity to the formation of transmembrane pores which were detected by electron microscopy in erythrocyte membranes is discussed. Circular dichroism studies indicated a self-association of the monomeric random coil form with increasing peptide concentration leading to the apparent induction of strong alpha-helix formation (approximately 100% helicity) in the fully aggregated state. However, no pH-dependent helix-random coil transition was observed, implying that interhelical hydrophobic and ionic interactions not only govern the self-association but also decisively influence the conformational stability of the peptide.

Synthesis of D-glucose 3- and 6-[2-(perfluoroalkyl)ethyl] phosphates: a new type of anionic surfactant for biomedical use

D-Glucose 3- and 6-[sodium 2-(perfluoro-hexyl or -octyl)ethyl phosphates) have been synthesized by condensation of 1,2,3,4,-tetra-O-acetyl-beta-D-glucopyranose and 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose with 2-(perfluoroalkyl)ethylphosphoroditriazolides followed by O-deacetylation or deacetalation. The structures of the compounds were established on the basis of 1H-, 19F-, 31P-, and 13C-NMR data. These salts display strong surface activities and appear to have good biocompatibility.

The influence of various amphiphilic phosphates on in vitro caries lesion formation in human dental enamel

Some newly designed surface-active phosphates were investigated with respect to their capacity to inhibit caries lesion formation in vitro. On the labial or buccal surfaces of sound human third molars, windows were prepared for investigation. One half of each window was treated with the test compound at pH values of 7.5, 5.5, or 3.5. The other half served as a control. Both halves were demineralized and the generated caries lesions in both parts were compared by means of quantitative microradiography. Mono-, bis- and trisphosphates differed only marginally in their effect on the demineralization. The compounds diminished the demineralization down to 30% of that of untreated enamel. Per molecule at least one long alkyl chain (more than 12 C atoms) was required for achieving decreased demineralization, indicating the importance of a low surface tension. The results suggest that some of the tested compounds have promising properties for their use as anticaries agents, especially when applied in combination with fluoride.

Syntheses, interfacial active properties and toxicity of new perfluoroalkylated surfactants

New surfactants have been synthesized with perfluorohexyl-groups as hydrophobic tail, a polyethyleneglycol-methylether as hydrophilic head and a prolongator between them. The prolongator units are -C4H8-, -C2H4OC5H10-, -C2H4OC3H6C(O)- and -CH2CH(OEt)CH2-. The surface tension, CMC and the interfacial tension water/perfluorocarbon were measured and the surface excess concentrations of the surfactant molecules were calculated. The influence of the surfactants on in vitro proliferation of human cell lines Hela and Molt 4 was investigated as a parameter for biocompatibility. The influence of the surfactants led to a reduction of cell proliferation depending on the concentration and chemical nature of the surfactant. Thus the prolongators changed the properties of the surfactants. They reduced the interfacial tension water/perfluorocarbon and improved the biocompatibility of surfactants.

Sensitized room-temperature luminescence in reverse micelles using lanthanide counterions as acceptors

The analytical usefulness of sensitized room-temperature luminescence in reverse micelles using lanthanide counterions is examined. The technique is based on the unique luminescent properties of tripositive lanthanide metal ions as counterions for the surfactant and the molecular organization produced by reverse micelles. After excitation, the analyte molecule transfers its triplet-state energy to an acceptor molecule (lanthanide), which subsequently emits luminescence. Two surfactants with different lanthanide counterions have been synthesized and characterized by spectroscopic and mass spectrometric techniques. When compared to the lanthanide salt, the sensitized luminescence of the lanthanide surfactant is substantially enhanced. The exact locations of the analyte and the counterion in the micellar system are discussed. The efficiencies of energy transfer for the two surfactants are compared.

Synthesis of perfluoroalkylated xylitol ethers and esters: new surfactants for biomedical uses

New, well-defined surfactants and cosurfactants were synthesized with the objective of enhancing the stability of fluorocarbon emulsions destined to serve as oxygen carriers for biomedical applications. Monoperfluoroalkylated ethers of xylitol were achieved by addition of perfluoroalkyl iodide on the double bond of a protected xylitol allyl ether in a one-step addition-elimination reaction. Monoesters were obtained specifically on position 5 by treating 1,2:3,4-di-O-isopropylidenexylitol with perfluoroalkylated acid chlorides of various chain lengths in pyridine at room temperature. The products display strong surface activity and produce a remarkable synergistic stabilization of a fluorocarbon/Pluronic F-68 type emulsion. Biocompatibility data are reported, which include in vitro toxicity tests on Namalva cell cultures and hemolysis tests on human blood cells; the latter was found to decrease as the length of the F-alkyl chain increased. IV injection in mice (n = 10) showed that these products were innocuous at 400-1000 mg/kg of body weight. Preliminary exchange-perfusion experiments on rats with an emulsion containing the F-octyl xylitol ether were encouraging.

Amidosulfobetaines, a family of detergents with improved solubilization properties: application for isoelectric focusing under denaturing conditions

The synthesis of a family of new detergents and their use for isoelectric focusing are described. These detergents differ from the conventional sulfobetaines by the presence of an amido group bridging the hydrophobic linear tail and the polar head, which increases their water solubility and urea tolerance considerably. Four different linear alkyl hydrophobic tails were tested, together with three different polar heads. The solubilization of red blood cell ghosts by the 12 resulting detergent performances was evaluated both in solution and in isoelectric focusing runs. Six chemicals gave performances equal or better than those of conventional detergents and could replace them for general use in focusing experiments. In addition, the synthesis of a whole range of compounds allowed valuable insights in the empirical understanding of protein-detergent interactions, which are extensively discussed.

Synthesis and characterization of 6-O-(N-heptylcarbamoyl)-methyl-alpha-D-glucopyranoside, a new surfactant for membrane studies

A new surfactant, 6-O-(N-heptylcarbamoyl)-methyl-alpha-D-glucopyranoside (HECAMEG, molar mass 335.38 g), was synthesized by a simple and low cost procedure from methyl-alpha-D-glucopyranoside. This surfactant is characterized by a high solubility in water (even at 0 degree C), ultraviolet light transparency in the region useful for protein detection, and a high critical micellar concentration (CMC = 19.5 mM), permitting fast elimination by dialysis. Furthermore, the surfactant is colorimetrically titratable by the anthrone technique and its weak interference in protein titration by the Lowry et al. procedure and the bicinchoninic method is easy to overcome. Two membrane proteins (NADH oxidase and succinate dehydrogenase) and a soluble enzyme (lactoperoxidase) retained full activity in the presence of HECAMEG below or above its CMC. The partial inhibition of beta-lactamase (soluble form) by HECAMEG above the CMC was probably only apparent and due to an interference of the surfactant with the substrate rather than a direct effect on the enzyme. HECAMEG was capable of extracting up to 75% of bacteriorhodopsin from the purple membrane of Halobacterium halobium in a nondenatured form as indicated by the spectral properties of the protein. It also solubilized spiralin from the Spiroplasma melliferum membrane with a great selectivity and efficiency, without detectable loss of antigenic properties. These data show that HECAMEG is a very mild surfactant, useful for membrane protein studies.

Supramolecular surfactants: amphiphilic polymers designed to disrupt lipid membranes

Simple polyesters derived from poly(ethylene glycol)s and alpha, omega-dicarboxylic acids exhibit a broad range of activity in disrupting phospholipid membranes. This activity has been analyzed by measuring the release of liposome-encapsulated 5(6)-carboxy-fluorescein (CF). Comparison with an analogous monomeric surfactant, and with Triton X-100, demonstrates that macromolecular activity is a sensitive function of the size of the hydrophobic and hydrophilic segments within each repeat unit, and that high disrupting power is possible. In vitro studies with the human immunodeficiency virus type-1 have revealed that those polyesters which exhibit the highest membrane disrupting power also provide significant protection for human CD4+ lymphocytes against HIV-1. The potential for adjusting and utilizing these "supramolecular surfactants" in medicine is briefly discussed.

Reversible conversion of octadecyl-bonded silica to ion-exchange surfaces for protein separations

Octadecyl-bonded silica, commonly used for reverse-phase high-pressure liquid chromatography, was modified using surfactants bearing ionizable groups and the modified packing used in ion-exchange chromatography of proteins. The surfactants 2-(n-hexadecylheptaethoxy)acetic acid, 1-(n-hexadecyloctaethoxy)ethylene-diamine, and N-(n-hexadecyloctaethoxy)pyridinium were adsorbed onto test columns packed with octadecyl-bonded silica particles. The proteins lysozyme, bovine serum albumin, trypsin, horse serum cholinesterase, and bovine liver carboxylesterase were used to study the ion-exchange characteristics of the modified packings. The retention order of the proteins on the surfactant-modified stationary phases were as predicted by the isoelectric point of each protein. In addition, the interaction of enzymes with the packings did not result in significant loss of enzymatic activity. Surfactant removal was possible with the use of organic solvents and this allowed the octadecyl-bonded surface to be used again in the reverse-phase mode. During the course of the experiments, no degradation in the packing's performance was observed due to loss of adsorbed surfactant, even after over 85,000 column volumes of sodium chloride and Tris-HCl buffers were circulated through the column.

Design, synthesis and evaluation of fluorocarbons and surfactants for in vivo applications. New perfluoroalkylated polyhydroxylated surfactants

The progress achieved since the advent of Fluosol-DA is summarized in this paper, with special focus on the synthesis and evaluation of more adequate, reliable, industrially feasible fluorocarbons, structure/property relationships--molecular weight being recognized as the pre-eminent determining factor of both the fluorocarbon's excretion rate and the emulsion's stability-, the preparation of significantly more concentrated, more efficacious emulsions, etc. The key to further progress and better mastery of the emulsions' characteristics, especially in relation to increased shelf-life, prolonged i.v. persistence, and versatility, now lies in the development of new surfactants, better adapted to this objective. New families of well defined, monodisperse perfluoroalkylated polyhydroxylated surfactants derived from sugars and related compounds have been synthesized and fully characterized. Preliminary evaluation of their surface-active properties, emulsion stabilizing capacity and biocompatibility are reported.

Deoxylysolecithin and a new biphenyl detergent as solubilizing agents for bovine rhodopsin. Functional test by formation of metarhodopsin II and binding of G-protein

The protein-detergent interaction in rhodopsin-detergent micelles has been investigated by using formation of metarhodopsin II (MII) as a monitor. Two detergents of different structural rigidity have been applied. One of them is [3-(lauroyloxy)propyl]phosphorylcholine, which has a high conformational flexibility in its hydrophobic moiety like most of the known detergents for rhodopsin. This deoxylysolecithin was originally designed as a detergent for membrane proteins by Weltzien [Weltzien, H. U. (1979) Biochim. Biophys. Acta 559, 259-287]. The other detergent, which is highly rigid in its hydrophobic part, has been developed for this study. It consists of a biphenyl derivative and a hydrophilic octaethylene oxide group. Both the formation kinetics of MII and the position of its equilibrium with its tautomeric form, metarhodopsin I (MI), strongly differed in the deoxylysolecithin and biphenyl detergent. Deoxylysolecithin caused very fast MII formation and shifted the equilibrium strongly to MII, like other detergents with alkyl chains as the hydrophobic part. In the biphenyl detergent, however, formation of MII was slow and the MI/MII equilibrium similar to that in the native system. For rhodopsin reconstituted in lipid bilayers, normal MII formation requires a well-adjusted fluidity of the hydrocarbon environment of the protein [Baldwin, P. A., & Hubbell, W. L. (1984) Biochemistry 24, 2633-2639], which was explained by an appropriate interfacial pressure at the protein-lipid interface. Extension of this concept would indicate that in the micellar core a degree of fluidity comparable to that of the disk membrane is just achieved with the highly rigid biphenyl structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of n-octyl-beta-D-thioglucoside, a new nonionic detergent, for solubilization and reconstitution of membrane proteins

n-Octyl-beta-D-thioglucopyranoside (octylthioglucoside), a new nonionic detergent, was synthesized. Properties of this detergent and its applicability to membrane biochemistry were investigated. The critical micelle concentration of this detergent was determined to be 9 mM. Membrane proteins of Escherichia coli were effectively solubilized with octylthioglucoside at 25-35 mM. The solubilizing power was equivalent to that of n-octyl-beta-D-glucopyranoside (octylglucoside). Reconstitution of the melibiose carrier into liposomes was performed by the detergent dilution procedure. It was found that the concentration range of octylthioglucoside for successful reconstitution (45-70 mM) was considerably wider than that of octylglucoside (43-46 mM), thus giving more reproducible results. Octylthioglucoside is more stable than octylglucoside. Furthermore, the former is synthesized with high yield at low cost whereas the latter is very expensive. Thus, we conclude that octylthioglucose is superior to octylglucoside, and is very useful in membrane biochemistry.

Sulfobetaine derivatives of bile acids: nondenaturing surfactants for membrane biochemistry

The syntheses of four new sulfobetaine derivatives of bile salts are presented, along with a general set of criteria for useful detergents in membrane biochemistry. Physical properties including the critical micelle concentration, aggregation number, partial specific volume, critical micellar temperature, uv-vis spectrum, and circular dichroism spectrum are examined for the new compounds. To examine the interaction of this class of compounds with macromolecules, one of these (CHAPS) was further studied. Circular dichroism spectra of apolipoprotein C-III2 were measured in the presence of varying concentrations of CHAPS to determine the effect of this compound on secondary structure. Gel-exclusion chromatography and sedimentation equilibrium studies of cytochrome P-450 in the presence of CHAPS were also performed to establish the ability of this detergent to disaggregate cytochrome P-450 to a monomeric/dimeric state.

Synthesis of 14C-labeled alkyl polyoxyethylene detergents

Procedures for the synthesis and purification of two 14C-labeled alkyl polyoxyethylene detergent preparations are described. One of the preparations consisted mainly of [14C]dodecyloctaoxyethylene ether, the other consisted mainly of [14C] octylhexaoxyethylene ether, with critical micellar concentrations of approximately 50 microM and 10 mM, respectively. Condensation of alkyl bromides with fractionated polyethyleneglycol resulted in less polydisperse products than conventional ethylene oxide condensation. Highly purified detergent species could easily be obtained from the preparations by thin-layer chromatography. Their use as tracers greatly simplifies determination of detergent concentration during protein solubilization and fractionation.

N-D-Gluco-N-methylalkanamide compounds, a new class of non-ionic detergents for membrane biochemistry

N-d-Gluco-N-methylalkanamide detergents have been synthesized. The detergents, which were produced in high yield and at low cost, compared favourably in biochemical studies with commonly used non-ionic detergents, including a chemically related n-alkyl glucoside. The ease of removal by dialysis, high solubilizing power and non-denaturing properties of this new class of detergents make them valuable reagents for membrane research.

A nondenaturing zwitterionic detergent for membrane biochemistry: design and synthesis

The synthesis and evaluation of a new detergent that is a zwitterionic derivative of cholic acid is presented. This detergent combines the useful properties of both the sulfobetaine-type detergents and the bile salt anions. The new detergent proved to be effective at solubilizing membrane proteins in a nondenatured state.

Adhesive bonding of various materials to hard tooth tissues: XIII Synthesis of a polyfunctional surface-active amine accelerator

Surface-active amine polymerization accelerators can be prepared by the reaction of polyepoxy resins with the sodium salt of N-phenylglycine and N-methyl-p-toluidine. These materials are expected to promote adhesion through complexation with surface calcium (or other metal ions), utilizing several chelating groups per molecule, and by functioning as polymerization accelerators for dental resins; they can also function as catalysts for the anionic polymerization of cyanoarylate monomers.

Preparation of laurylsarcosyltaurine: a surface active constituent of crab gastric juice

The conditions for the preparation of laurylsarcosyltaurine from lauric acid and sarcosyltaurine, a crystalline dipeptide, are described. The preparation of sarcosyltaurine from the reaction of taurine and the mixed anhydride of benzyloxycarbonylsarcosine and isobutyl chloroformate is also described.

Synthesis and CMC determination of a series of aliphatic diamines

Fifteen aliphatic diamines substituted with one long alkyl chain (C10-C18), a varying number of methylene groups separating the nitrogens (two to six), and various aliphatic substituents were synthesized and their CMC's were determined. While the length of the long alkyl chain plays a dominant role in influencing the CMC, the other N-alkyl substituents as well as the length of the methylene chain separating the two nitrogens of the diamine are significant factors.