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Hydrophilic Groups (hydrophilic + groups)
Selected AbstractsLocalization and interactions of melatonin in dry cholesterol/lecithin mixed reversed micelles used as cell membrane modelsJOURNAL OF PINEAL RESEARCH, Issue 4 2005David Bongiorno Abstract:, The state of melatonin confined in dry cholesterol/lecithin mixed reversed micelles dispersed in CCl4 was investigated using 1H-NMR and FT-IR spectroscopies as a function of the melatonin to lecithin molar ratio (RMLT) and of the cholesterol to lecithin molar ratio (RCHL). An analysis of experimental results leads to the hypothesis that, independent of RMLT and as a consequence of anisotropic melatonin/lecithin, melatonin/cholesterol and cholesterol/lecithin interactions, melatonin is totally solubilized in reversed micelles. Melatonin is mainly located in and oriented in the nanodomain constituted by the hydrophilic groups of cholesterol and lecithin. A competition of melatonin and cholesterol for the hydrophilic binding sites of the reversed micelles was observed by changing the RCHL. Some possible biological implications of the specific interactions governing the solubilization process, the preferential location and the peculiar properties of melatonin confined in cholesterol/lecithin mixed reversed micelles are discussed. [source] Crystal packing in the structures of diethanolamine derivativesACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2009Andrei V. Churakov Four distinct hydrogen-bonding topologies were observed in the structures of six diethanolamine ligands. These compounds are (1R*,2R*)-2-[(2-hydroxyethyl)(methyl)amino]-1,2-diphenylethanol, C17H21NO2, (I), 1-[(2S)-2-(hydroxydiphenylmethyl)pyrrolidin-1-yl]-2-methylpropan-2-ol, C21H27NO2, (II), 2-[(2-hydroxyethyl)(methyl)amino]-1,1-diphenylethanol, C17H21NO2, (III), 1-{(2-hydroxy-2-methylpropyl)[(1S)-1-phenylethyl]amino}-2-methylpropan-2-ol, C16H27NO2, (IV), 1-{[(2R)-2-hydroxy-2-phenylethyl][(1S)-1-phenylethyl]amino}-2-methylpropan-2-ol, C20H27NO2, (V), and (1R*,2S*)-2-[(2-hydroxyethyl)(methyl)amino]-1,2-diphenylethanol, C17H21NO2, (VI). In each compound, all `active' hydroxy H atoms are engaged in hydrogen bonding, but the N atoms are not involved in intermolecular hydrogen bonding. In the structures of (I), (II) and (IV),(VI), molecules are linked into chains by intermolecular O,H...O interactions. These chains are organized in such a way as to hide the hydrophilic groups inside, and so the outer surfaces of the chains are hydrophobic. The structure of (VI) contains two distinct non-equivalent systems of intermolecular O,H...O hydrogen bonds formed by disordered hydroxy H atoms. [source] Hydration of polysaccharide hyaluronan observed by IR spectrometry.BIOPOLYMERS, Issue 1 2003Abstract This article is the first one in a series dedicated to the study of hyaluronan as observed by IR spectrometry. The goal is to determine its hydration mechanism and the structural changes this mechanism implies. Hyaluronan is a natural polysaccharide that is widely used in biomedical applications and cosmetics. Its macroscopic properties are significantly dependent on its degree of hydration. In this article we record the IR spectrum of a several micron thick dried film and deduce that four or five residual H2O molecules remain around each disaccharide repeat unit in the dried film. We then compare the spectra of sodium hyaluronan and its acid form to assign vibrational bands linked to the carboxylate group. We proceed with a qualitative analysis of the spectral changes induced by changes of temperature and hygroscopicity, two independent parameters that act by modifying the hydrogen bond network of the sample. This enables us to assign most of the vibrational bands of the hydrophilic groups and to distinguish the bands that are due to these hydrophilic groups when they are or are not hydrogen bonded. It constitutes a prerequisite for the quantitative analysis of hydration spectra that will be described in the following articles of this series. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 10,20, 2003 [source] A study of novel bisazo reactive red dyes with good wet fastnessCOLORATION TECHNOLOGY, Issue 4 2009Zhuan Wang Three series of bisazo reactive red dyes were synthesised using 6-amino-1-naphthol-3-sulphonic acid and its derivatives as the coupling components. The dyeing parameters and wash fastness of these dyes on knitted cotton were evaluated and the relationships between the structure and dyeing properties were investigated. It was found that the hydrophilic groups introduced into the dye molecules decrease the substantivity and fixation of the dyes, but increase the build-up and migration properties. The defined wash-off factor can directly reflect the wash fastness of the dyes and the build-up property can be improved by commercialisation using certain auxiliaries. The results indicate that there is the possibility of synthesising a red reactive dye with a satisfying balance between high fixation and good wash fastness and several such dyes have been developed. [source] | ||||||||||