Low concentrations of bile salts increase the rate of spontaneous phospholipid transfer between vesicles.
Low concentrations of bile salts increase the rate of spontaneous phospholipid transfer between vesicles.
复制标题
低浓度的胆汁盐会增加囊泡之间自发磷脂转移的速率。
DOI：
10.1021/bi00364a021
复制
发表时间：
1986
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：
Nichols,JW
Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322 Received October 2, 1985; Revised Manuscript Received April 3, 1986 abstract: The rate of 1-palmitoyl-2-[12-[(7-nitro-2, 1, 3-benzoxadiazol-4-yl) amino] dodecanoyl] phosphatidylcholine (P-C12-NBD-PC) transfer between dioleoylphosphatidylcholine vesicles was measured by a technique based on resonance energy transfer between P-C12-NBD-PC and 7V-(lissamine rhodamine B sulfonyl) dioleoylphosphatidylethanolamine [Nichols, J. W., & Pagano, R. E.(1982) Biochemistry 21, 1720-1726], Addition of bile saltsat concentrations below their critical micelle concentrationsincreased the rate of spontaneous P-C12-NBD-PCtransfer without disrupting thevesicles. The effectiveness in increasing the transfer rate was dependent on the structure of the bile salt. In general, conjugated bile salts were more effective than unconjugated, and mono-and dihydroxy bile salts were more effective than trihydroxy. The kinetics of intervesicular P-C12-NBD-PC transfer in the presence of cholate were found to be consistent with a mass action kinetic model based on the premise that bile salts bind to the vesicles, alter the dissociation and/or association rate constants for phospholipid monomer-vesicle interaction, and increase the rate of phospholipid transfer via the diffusion of soluble monomers through the aqueous phase. Temperature dependence studies indicated that cholate binding to vesicles is an entropy-driven process and that cholate binding lowers the free energy of activation for phospholipid monomer-vesicle dissociation by producing compensatory decreases in both the enthalpy and entropy of activation.^^^ lospholipids spontaneously transfer between membranes by the diffusion of soluble monomers through the aqueous bulk phase (Duckwitz-Peterlein et al., 1977; Roseman & Thompson, 1980; McLean & Phillips, 1981, 1984; Nichols & Pagano, 1981, 1982; Massey et al., 1982a, b; Decuyper et al., 1983; Ferrell et al., 1985). This paper demonstrates that concen-f This study was supported by US Public Health Service Grant GM 32342 and an Emory University Research Grant. trations of bile salts below their critical micelle concentrations bind to membranesand increase the spontaneous rate of intervesicular phospholipid transfer. The simplest explanation for this effect is that bile salts increase the rate of spontaneous transfer by partitioning into the membranes and altering the dissociation and/or association rate constants for phospholipid monomer-vesicle interaction. This paper presents a model based on this premise using the principles of mass action kinetics and demonstrates that this model can predict the initial
