87 results found
Hamid HAA, Hashim R, Seddon JM, et al., 2014, Lyotropic phase behaviour and structural parameters of monosaccharide and disaccharide guerbet branched-chain β-D-glycosides, Advanced Materials Research, Vol: 895, Pages: 111-115, ISSN: 1022-6680
The phase behaviour and self-assembly structural parameters of a pair of monosaccharide and disaccharide Guerbet branched-chain β-D-glycosides, namely 2-octyldodecyl β-D-glucoside (β-Glc- C12C8) and 2-octyldodecyl β-D-maltoside (β-Mal- C12C8), have been studied by means of optical polarizing microscopy (OPM) and small-angle X-ray diffraction at room temperature (25°C). These compounds are sugar-based glycolipid surfactants having a total chain length of C20, and differ based on the increasing number of hydroxyl groups of the sugar headgroup (glucose and maltose). The repeat spacings obtained by X-ray diffraction as a function of water content have been used to determine the limiting hydration for the two glycosides. At room temperature, β-Glc-12C8 and β- Mal- C12C8 have limiting hydrations of 22 wt% and 25 wt%, corresponding to 8 - 10 and 10 - 12 water molecules per glycoside, respectively. At all water contents between 5 and 29 wt % water, these compounds adopt inverse hexagonal (HII) or fluid lamellar (Lα) phases. The structural parameters of these phases have been determined from the diffraction data, from the X-ray repeat spacings, densities and concentration of the glycosides. © (2014) Trans Tech Publications, Switzerland.
Karamdad K, Brooks N, Ces O, 2014, Microfluidic generation of asymmetric giant unilamellar vesicles, Pages: 339-341
© 14CBMS. We have developed a novel microfluidic platform to generate asymmetric giant unilamellar vesicles (GUVs). Water-in-oil (W/O) droplets formed in a lipid-containing oil flow are transferred across an oil-water interface, facilitating the self-assembly of a phospholipid bilayer. We have confirmed the presence of unilameller lipid bilayers in each vesicle by incorporating fluorescently-tagged lipid into the membrane bilayer.
Cook AG, Martinez-Felipe A, Brooks NJ, et al., 2013, New insights into the transitional behaviour of methyl-6-O-(n-dodecanoyl)-alpha-D-glucopyranoside using variable temperature FTIR spectroscopy and X-ray diffraction, LIQUID CRYSTALS, Vol: 40, Pages: 1817-1827, ISSN: 0267-8292
Zahid NI, Conn CE, Brooks NJ, et al., 2013, Investigation of the Effect of Sugar Stereochemistry on Biologically Relevant Lyotropic Phases from Branched-Chain Synthetic Glycolipids by Small-Angle X-Ray Scattering, Langmuir
Synthetic branched-chain glycolipids are suitable as model systems to understand biological cell membranes, particularly since certain natural lipids possess chain branching. Herein, four branched-chain glycopyranosides namely 2-hexyl-decyl-α-D-glucopyranoside (α-Glc-OC10C6), 2-hexyl-decyl-β-D-glucopyranoside (β-Glc-OC10C6), 2-hexyl-decyl-α-D-galactopyranoside (α-Gal-OC10C6) and 2-hexyl-decyl-β-D-galactopyranoside (β-Gal-OC10C6) with a total alkyl chain length of 16 carbon atoms have been synthesized and their phase behaviour studied. The partial binary phase diagrams of these non-ionic surfactants in water were investigated by optical polarizing microscopy (OPM) and small-angle X-ray scattering (SAXS). The introduction of chain branching in the hydrocarbon chain region is shown to result in the formation of inverse structures such as the inverse hexagonal and inverse bicontinuous cubic phases. Comparison of the four compounds showed that they exhibited different polymorphism, especially in the thermotropic state, due to contributions from anomeric and epimeric effects according to their stereochemistry. The neat compound of α-Glc-OC10C6 exhibited a lamellar (Lα) phase whereas dry α-Gal-OC10C6formed an inverse bicontinuous cubic Ia3d (QIIG) phase. Both β-anomers of glucoside and galactoside adopted the inverse hexagonal phase (HII) in the dry state. Generally, in the presence of water, all four glycolipids formed inverse bicontinuous cubic Ia3d (QIIG) and Pn3m (QIID) phases over a wide temperature and concentration range. The formation of inverse non-lamellar phases by these Guerbet branched-chain glycosides confirms their potential as materials for novel biotechnological applications such as drug-delivery and crystallization of membrane proteins.
Purushothaman S, Gauthe BLLE, Brooks NJ, et al., 2013, Automated laboratory based X-ray beamline with multi-capillary sample chamber, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 84, ISSN: 0034-6748
Zahid IN, Conn CE, Brooks NJ, et al., 2013, Effects of sugar stereochemistry on lyotropic mesophases of branched-chain synthetic glycolipids, 9th European-Biophysical-Societies-Association Congress, Publisher: SPRINGER, Pages: S132-S132, ISSN: 0175-7571
Tyler AII, Shearman GC, Parsons ES, et al., 2013, Tuning curvature in inverse micellar and bicontinuous cubic phases, 9th European-Biophysical-Societies-Association Congress, Publisher: SPRINGER, Pages: S140-S140, ISSN: 0175-7571
Johnson S, Brooks NJ, Smith RAG, et al., 2013, Structural basis for recognition of the pore-forming toxin intermedilysin by human complement receptor CD59, Cell Reports, Vol: 3
Pore-forming proteins containing the structurally conserved membrane attack complex/perforin fold play an important role in immunity and host-pathogen interactions. Intermedilysin (ILY) is an archetypal member of a cholesterol-dependent cytolysin subclass that hijacks the complement receptor CD59 to make cytotoxic pores in human cells. ILY directly competes for the membrane attack complex binding-site on CD59, rendering cells susceptible to complement lysis. To understand how these bacterial pores form in lipid bilayers and the role CD59 plays in complement regulation, we determined the crystal structure of human CD59 bound to ILY. Here we show the ILY-CD59 complex at 3.5 Å resolution and identify two interfaces mediating this hostpathogen interaction. An ILY-derived peptide based on the binding-site inhibits pore formation in a CD59-containing liposome model system. These data provide insight into how CD59 coordinates ILY monomers, nucleating an early prepore state, and suggest a potential mechanism of inhibition for the complement terminal pathway.
Cook AG, Wardell JL, Brooks NJ, et al., 2012, Non-symmetric liquid crystal dimer containing a carbohydrate-based moiety, Carbohydrate Research, Vol: 360, Pages: 78-83
The synthesis and characterisation of a novel non-symmetric liquid crystal dimer, 1-[3-O-(D-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-40-oxy)]octane is reported. This exhibits glassy behaviour and a highly interdigitated smectic A phase in which the aromatic and alkyl structural fragments overlap. Variable temperature infrared spectroscopy reveals that the strength and extent of hydrogen bonding within the system does not show a marked change at either the glass transition or at the smectic A-isotropic transition. This observation indicates that the smectic A-isotropic transition is driven by changes in the van der Waals interactions between the molecules while hydrogen bonded aggregates persist into the isotropic phase.
Tang TYD, Brooks NJ, Jeworrek C, et al., 2012, Hydrostatic Pressure Eﬀects on the Lamellar to Gyroid Cubic Phase Transition of Monolinolein at Limited Hydration, Langmuir
Shaw KP, Brooks NJ, Clarke JA, et al., 2012, Pressure – temperature phase behaviour of natural sphingomyelin extracts, Soft Matter, Vol: 8, Pages: 1070-1078
Sphingomyelin is the only sphingolipid occurring naturally in mammalian cells and can form up to 50% of the total phospholipid content of the myelin sheath which surrounds nerves. Having predominantly long, saturated acyl chains, it has a relatively high chain melting temperature and has been strongly associated with formation of lipid microdomains. Here, the lyotropic phase behaviour of sphingomyelin from three different natural sources (bovine brain, egg yolk and milk) in excess water is studied as a function of temperature and pressure by small- and wide-angle X-ray scattering, and solid state NMR. The different hydrocarbon chain length distributions of the three lipid extracts results in significant differences in their gel phase structure; both the bovine brain and egg yolk sphingomyelins can form a ripple gel phase but milk sphingomyelin forms an interdigitated gel phase due to the high degree of chain mismatch in its longer hydrocarbon chain components.
Furse S, Brooks NJ, Seddon AM, et al., 2012, Lipid membrane curvature induced by distearoyl phosphatidylinositol 4-phosphate, Soft Matter
Brooks NJ, Ces O, Templer RH, et al., 2011, Pressure effects on lipid membrane structure and dynamics, CHEMISTRY AND PHYSICS OF LIPIDS, Vol: 164, Pages: 89-98, ISSN: 0009-3084
Richardson RM, Hanna S, Brooks NJ, et al., 2011, Columnar Phases in Liquid Crystal Dendrimers: Variable Pressure X-Ray Diffraction, MOLECULAR CRYSTALS AND LIQUID CRYSTALS, Vol: 541, Pages: 415-425, ISSN: 1542-1406
Shearman GC, Brooks NJ, Tiddy GJT, et al., 2011, A lyotropic inverse ribbon phase in a branched-chain polyoxyethylene surfactant: pressure effects, SOFT MATTER, Vol: 7, Pages: 4386-4390, ISSN: 1744-683X
Tyler AII, Shearman GC, Brooks NJ, et al., 2011, Hydrostatic pressure effects on a hydrated lipid inverse micellar Fd3m cubic phase, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 3033-3038, ISSN: 1463-9076
Brooks NJ, Hamid HAA, Hashim R, et al., 2011, Thermotropic and lyotropic liquid crystalline phases of Guerbet branched-chain β-D-glucosides, Liquid Crystals, Vol: 38, Pages: 1725-1734
The effect of chain branching on glycolipid thermotropic and lyotropic phases was investigated for a series ofsynthetic β-D-glucosides derived from Guerbet alcohols, whose total hydrocarbon chain length ranged from C8 toC24. The compounds, which can be viewed as isosteric mimics for glycoglycerolipids, were synthesised in high purityand their liquid crystalline phases were studied using optical polarising microscopy (OPM), and small-angle X-raydiffraction.When dry, the shortest compound (total C8) exhibits a monotropic Lα phase while longer ones (C16 andC20) adopt inverse hexagonal HII phases. The C24 compound forms an ordered lamellar phase at room temperature,but exhibits a metastable HII phase upon cooling. Curiously the intermediate chain length homologue (C12) adoptsan isotropic inverse micellar (L2) phase in the dry state over the range of temperatures studied. Upon hydration,the C8 compound dissolves, and the C12 compound forms a fluid lamellar Lα phase. The C16 Guerbet glucoside (i.e.β-Glc-C10C6) exhibits an inverse bicontinuous cubic phase of space group Ia3d in excess water, never previouslyobserved in branched-chain lipids, and very seldom observed in excess water. The C20 compound remains in theHII phase upon hydrating, with the lattice parameter swelling substantially.
Richardson R, Hanna S, Brooks NJ, et al., 2011, Columnar phases in liquid crystal dendrimers: Variable pressure X-ray diffraction, International Liquid Crystals Conference
Brooks NJ, Gauthe BLLE, Terrill NJ, et al., 2010, Automated high pressure cell for pressure jump x-ray diffraction, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 81, ISSN: 0034-6748
Shearman GC, Tyler AII, Brooks NJ, et al., 2010, Ordered micellar and inverse micellar lyotropic phases, LIQUID CRYSTALS, Vol: 37, Pages: 679-694, ISSN: 0267-8292
Tyler AII, Shearman GC, Brooks NJ, et al., 2010, High Pressure Static and Time-Resolved X-Ray Studies of Inverse Phases in Cholesterol / Lipid Mixtures, BIOPHYSICAL JOURNAL, Vol: 98, Pages: 231A-231A, ISSN: 0006-3495
Martin HP, Brooks NJ, Seddon JM, et al., 2010, Complex fluids under microflow probed by SAXS: rapid microfabrication and analysis, 14th International Conference on Small-Angle Scattering (SAS09), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Baldwin GS, Brooks NJ, Robson RE, et al., 2009, DNA Double Helices Recognize Mutual Sequence Homology in a Protein Free Environment, JOURNAL OF BIOMOLECULAR STRUCTURE & DYNAMICS, Vol: 26, Pages: 880-880, ISSN: 0739-1102
Dreiss CA, Nwabunwanne E, Liu R, et al., 2009, Assembling and de-assembling micelles: competitive interactions of cyclodextrins and drugs with Pluronics, SOFT MATTER, Vol: 5, Pages: 1888-1896, ISSN: 1744-683X
Amos KE, Brooks NJ, King NC, et al., 2008, A systematic study of the formation of mesostructured silica using surfactant ruthenium complexes in high- and low-concentration regimes, JOURNAL OF MATERIALS CHEMISTRY, Vol: 18, Pages: 5282-5292, ISSN: 0959-9428
Baldwin GS, Brooks NJ, Robson RE, et al., 2008, DNA double helices recognize mutual sequence homology in a protein free environment, J. Phys. Chem. B, Vol: 112, Pages: 1060-1064
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