講者：Prof. Jeffery B. Klauda
演講題目：The influence of Alcohols on the Oil/Water Interface and Cell Membranes
演講時間：10/28（五）15:30~17:20
演講地點：博雅館 201
主持人：蔡偉博教授
The Influence of Alcohols on the Oil/Water Interface and Cell Membranes
Alcohols have a wide range of applications from ethanol’s common use in beverages to being an antiseptic, solvent and fuel. These molecules are naturally amphiphilic with the hydroxyl group liking water and a hydrocarbon group of varying length that dislikes water. These compounds can be classified as a hydrotrope, which by definition are small amphiphilic molecules that increase the solubility of weakly soluble compounds in water. Tert-butyl alcohol (TBA) has intriguing solution properties in water at concentrations less than 10 mol%, e.g., maximal heat capacity and activity coefficient less than one. If mixed with an oil, TBA solutions form stable 100nm droplets. We have used all-atom molecular simulations to probe interesting structural behavior of TBA in water and with cyclohexane droplets and bulk interfaces. TBA acts much like a surfactant to reduce the oil/water interfacial tension by adsorbing at the oil/water interface. All isomers of butanol were probed to understand how variations in the hydrocarbon tail influence surface properties, with most of the significant difference occurring at concentrations of <10 mol% of butanol.
Alcohols also have strong influence in biology and alter the properties of cellular membranes. This is one limiting factor in microbial production of chemicals and fuels in that cells cannot survive in solutions that contain a moderate level of the produced chemical or fuel. Since cellular membranes consist of a wide array of lipid types, we have been studying the influence of lipid head group on its ability to protect the membrane from the toxic effects of ethanol. Molecular dynamics (MD) simulations have probed common lipids found in yeast plasma membranes and it was found that the phosphatidylcholine lipid was most influenced by ethanol and phosphatidylserine was the least. In collaboration with Dr. Laura Jarboe at Iowa State University, we are currently probing the effects of ethanol (and other chemicals) on the E. Coli inner membrane with a goal genetically alter lipid composition to develop more tolerant strains to chemical stress.
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