Hydrophobic interaction of lysophospholipids and bile salts at submicellar concentrations.
Hydrophobic interaction of lysophospholipids and bile salts at submicellar concentrations.
复制标题
溶血磷脂和胆汁盐在亚胶束浓度下的疏水相互作用。
DOI：
10.1021/bi00476a027
复制
发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Nichols,JW
中科院分区：
文献类型：
--
作者：
Shoemaker,DG;Nichols,JW
Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322 Received February 5, 1990; Revised Manuscript Received March 21, 1990 abstract: A series of environment-sensitive, fluorescent-labeled N-(7-nitro-2, l, 3-benzoxadiazol-4-yl)-monoacylphosphatidylethanolamine (TV-NBD-lysoPE) probes of differing acyl chain length (C12-C18) was used todemonstrate the hydrophobic interaction between lysophospholipids and two different bile salts at concentrations below their respective critical micelle concentrations (erne’s). Formation of submicellar aggregates in the presence of bile salt-phospholipid mixed micelles could facilitatelipid absorption in the intestine. To ensure the use of submicellar lysolipidconcentrations in the experiments, the cmc of each fluorescent lysolipid probe was determined by concentration-dependent self-quenching. The cmc values obtained for the various VV-NBD-lysoPE probes were as follows (µ): monolauroyl,> 40; monomyristoyl, 4; monopalmitoyl, 0.3; monostearoyl, 0.04. Probe concentrations well below their respective erne’s were used in all experiments. The fluorescence of a solution of each lysolipid probe was monitored as the concentration of bile salt was gradually increased. The increase in fluorescence was taken as a measure of the ability of the bile salt molecules to complex with the probe molecule, thereby increasing the fluorescent yield of the lysolipid probe molecule. Determination of the cmc of the bile salts in the presence of the lysolipid probe was made in parallel with the fluorescence measurement by monitoring the increase in light scattering of the solution. Both bile salts were shown to inducemaximal increases in fluorescence of the VV-NBD-lysoPE derivatives at concentrations of bile salt well below their respective cmc values, indicating the existence of submicellar lysolipid-bile salt aggregates. Examination of the data within the frameworkof the Hill equation model for cooperativity indicatedthat between two and five molecules were a minimum estimate for the number of bile salts required to give maximal fluorescence. The affinity of the bile salt—lysolipid interaction was found to increase with the hydrophobicity of both the bile salt (TDC> cholate) and the lysolipid (C18
