Chen L, Johnson M L, Biltonen R L
Department of Pharmacology and the Biophysics Program, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
Biophys J. 2001 Jan;80(1):254-70. doi: 10.1016/S0006-3495(01)76011-0.
A macroscopic model is presented to quantitatively describe lipid bilayer gel to fluid phase transitions. In this model, the Gibbs potential of the lipid bilayer is expressed in terms of a single order parameter q, the average chain orientational order parameter. The Gibbs potential is based on molecular mean-field and statistical mechanical calculations of inter and intrachain interactions. Chain-length and chain-asymmetry are incorporated into the Gibbs potential so that one equation provides an accurate description of mixed-chain phosphatidylcholines of a single class. Two general classes of lipids are studied in this work: lipid bilayers of partially or noninterdigitated gel phases, and bilayers of mixed interdigitated gel phases. The model parameters are obtained by fitting the transition temperature and enthalpy data of phosphatidylcholines to the model. The proposed model provides estimates for the transition temperature and enthalpy, van der Waals energy, number of gauche bonds, chain orientational order parameter, and bond rotational and excluded volume entropies, achieving excellent agreement with existing data obtained with various techniques.
提出了一个宏观模型来定量描述脂质双层从凝胶相到流体相的转变。在这个模型中,脂质双层的吉布斯势用单一的序参量q表示,即平均链取向序参量。吉布斯势基于分子平均场以及链间和链内相互作用的统计力学计算。链长和链不对称性被纳入吉布斯势中,这样一个方程就能准确描述单一类别的混合链磷脂酰胆碱。在这项工作中研究了两类一般的脂质:部分或非交错凝胶相的脂质双层,以及混合交错凝胶相的双层。通过将磷脂酰胆碱的转变温度和焓数据拟合到模型中来获得模型参数。所提出的模型提供了转变温度和焓、范德华能、扭曲键的数量、链取向序参量以及键旋转和排除体积熵的估计值,与通过各种技术获得的现有数据达成了极好的一致性。