Various new nucleosides bearing one or two lipophilic groups at the 2′-position have been synthesized. The lipophilic substituents were attached to a 2′-hydroxy, 2′-amino, or 2′-thio function. These lipophilic nucleosidesanchor in large unilamellar POPC vesicles serving as phospholipidmembrane models. The insertion of these molecules into the membranes was investigated by NMR techniques. For comparison
insights into their roles, we aimed to develop functionalized SSEA glycan analogs via chemical synthesis. Herein, we report a convergent synthetic approach for SSEA-3 and SSEA-4 analogs using readily available versatile building blocks. A key step, namely the stereoselective glycosylation of a common tetrasaccharide acceptor, was successfully achieved using a 4-O-Bn Gal donor for SSEA-3 and a Neu-Gal
Neutron Reflection from Hexadecyltrimethylammonium Bromide Adsorbed at the Air/Liquid Interface: The Variation of the Hydrocarbon Chain Distribution with Surface Concentration
作者:J. R. Lu、M. Hromadova、E. A. Simister、R. K. Thomas、J. Penfold
DOI:10.1021/j100095a037
日期:1994.11
We have determined the structure of a monolayer of hexadecyltrimethylammonium bromide adsorbed at the air/water interface at its critical micelle concentration (9.2 x 10(-4) M) and at two lower concentrations using neutron specular reflection. We have used isotopic labeling to determine the relative positions of chains, heads, and solvent, and more detailed labeling to determine the distributions of C-6 chain fragments at either end of the alkyl chains. The use of the more detailed labeling scheme has allowed us to make a quantitative estimate of the contribution of surface roughness to the structure of the layer at the three concentrations, to show that the alkyl chains are, on average, strongly tilted away from the surface normal but that the part of the alkyl chain next to the head group is less tilted. The different tilt angle distributions for the two ends of the hydrocarbon chain also indicate that there are gauche defects in the chain.