FTIR Evidence for Alcohol Binding and Dehydration in Phospholipid and Ganglioside Micelles

Abstract

We theorize that intoxicants and modern anesthetics bind at the membrane-water interface and displace (dehydrate) bound water molecules by breaking the hydrogen bonds. We tested this hypothesis by examining the effect of butanol on the binding of water to the polar regions of lipids in reversed micelles. Understanding the mechanisms of intoxication requires studies in physiologically relevant systems such as systems containing sialoglycoconjugates, especially gangliosides, which concentrate in the synapses of neural tissue. Therefore, we compared butanol effects on phospholipid with effects on ganglioside. Hydrogen-bond breaking activity of 1-butanol was studied in reversed micelles made of dipalmitoylphosphotidylcholine (DPPC), ganglioside (GM1 and GT1b) or the lipid mixture in a D2O-CCl4 medium. Fourier transform infrared spectroscopy (FTIR) data indicated that 1-butanol binds to DPPC and to gangliosides. Adding GM1 to the DPPC micelles introduces a new binding site for the alcohol. GT1b binds more butanol than GM1, because of more binding sites provided by extra sialic acid moieties. Spectral red shifts indicate that both water and butanol bind to the C = O group of sialic acid. Butanol partially releases the surface-bound water by disrupting hydrogen bonds, as indicated by an appearance of a sharp new free OD stretching band of the released D2O molecules. However, control studies with lipid-free systems in CCl4 revealed that a free OD peak could occur from a deuterium exchange reaction between D2O and 1-butanol(ol-h).(ABSTRACT TRUNCATED AT 250 WORDS)

Direct NMR Evidence for Ethanol Binding to the Lipid-Water Interface of Phospholipid Bilayers

“…It was also shown that water undergoes polar interactions with (CH3)3N+. The binding of ethanol at the lipid-water interface may perturb the inner hydration shell around the lipid headgroup, based on the release of bound water observed with FTIR (Chiou et al, 1992;Yurttas et al, 1992) and the decreased Avq for bound D2O in the current work. At the same time, however, it is possible that the increase in the area per lipid caused by ethanol binding (discussed below) may lead to an overall increase in the amount of partly ordered water associated with the lipid-water interface.…”

“…Also, a radio tracer study measuring the partitioning of ethanol between a membrane pellet and aqueous supernatant found that mouse brain synaptosomes had a partition coefficient 60 times higher than that for La phase dipalmitoylphosphatidylcholine (DPPC) bilayers (Sarasua et al, 1989), suggesting that in synaptosomes ethanol may be able to bind to a variety of polar groups, including those of proteins and carbohydrate groups. Fourier transform infrared (FTIR) studies of inverted micelles of DPPC and gangliosides (water in carbon tetrachloride) suggest that ethanol displaces some bound water at the micellar surface (Chiou et al, 1992;Yurttas et al, 1992). Data by Klemm and co-workers [reviewed in Klemm (1990)] suggest that the acute effects of ethanol in the brain could be mediated by changes in the hydrogen or electrostatic bonding between gangliosidic sialic acid and receptor proteins, due to the replacement of water with ethanol.…”

Effects of Short-Chain Alcohols and Pyridine on the Hydration Forces between Silica Surfaces

“…To answer this question, 5 g of BDH silica hydration forces, which may be the cause for the intoxication. Spectroscopic analysis of lipids membranes treated with was contacted with a 10 04 M pyridine solution of pH 6.0 for 20 min, and the supernatant solution was subjected to alcohols show evidence for the displacement of bound water (38,39). According to the force data obtained in the present UV analysis.…”

Low Doses of Ethanol Reduce Evidence for Nonlinear Structure in Brain Activity

“…The finding that ethanol can decrease the evidence for nonlinear structure in the EEG invites speculation as to how such findings might relate to theories of the actions of ethanol on brain and behavior. Recent theories suggest that ethanol may act on both proteins and lipids in neuronal membranes (Mander et al, 1985;Besson et al, 1989;Chiou et al, 1990;Klemm, 1990;Weight, 1992;Yurttas et al, 1992;Grant, 1994;Isobe et al, 1994;Li et al, 1994;Peoples et al, 1996). How such physical changes in the cellular milieu lead to intoxication at the behavioral and electrophysiological level, especially at lower doses, has not yet been elaborated.…”