Flicker spectroscopy of thermal lipid bilayer domain boundary fluctuations
Flicker spectroscopy of thermal lipid bilayer domain boundary fluctuations
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DOI：
10.1529/biophysj.107.111922
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发表时间：
2007-11-01
影响因子：
3.4
通讯作者：
Baumgart, Tobias
中科院分区：
文献类型：
--
作者：
Esposito, Cinzia;Tian, Aiwei;Baumgart, Tobias
这一贡献描述了测量脂质双层结构域线张力的基础上的二维热波动的膜与液体有序/液体无序相共存和近临界组合物在室温下。脂质和蛋白质组成的横向不均匀性是目前的一个热门研究课题，旨在确定膜结构域的基本性质和生物相关性。线张力在流体脂质双层膜域边界控制域生长的动力学，因此调节组成的异质性的大小。高线张力促进膜域出芽和分裂。因此，线张力可能是调节生物膜功能方面的重要控制参数。在这里，建立的流体域闪烁光谱的方法被应用于检查相分离双层膜的热畴壁波动。我们发现一个高斯概率分布的前几个激发模式的振幅，这允许通过适当的专门毛细管波理论的分析。发现时间自相关函数呈指数衰减，弛豫时间拟合通过流体力学理论有关线张力和激发模式弛豫动力学。线张力低于1 pN，这两种方法产生类似的结果。我们研究实验文物扰动域迹的傅立叶频谱，并讨论如何确定产生可靠的线张力信息的模式的数量。
This contribution describes measurements of lipid bilayer domain line tension based on two-dimensional thermal undulations of membranes with liquid ordered/liquid disordered phase coexistence and near-critical composition at room temperature. Lateral inhomogeneity of lipid and protein composition is currently a subject of avid research aimed at determining both fundamental properties and biological relevance of membrane domains. Line tension at fluid lipid bilayer membrane domain boundaries controls the kinetics of domain growth and therefore regulates the size of compositional heterogeneities. High line tension promotes membrane domain budding and fission. Line tension could therefore be an important control parameter regulating functional aspects of biological membranes. Here the established method of fluid domain flicker spectroscopy is applied to examine thermal domain wall fluctuations of phase-separated bilayer membranes. We find a Gaussian probability distribution for the first few excited mode amplitudes, which permits an analysis by means of appropriately specialized capillary wave theory. Time autocorrelation functions are found to decay exponentially, and relaxation times are fitted by means of a hydrodynamic theory relating line tensions and excited mode relaxation kinetics. Line tensions below 1 pN are obtained, with these two approaches yielding similar results. We examine experimental artifacts that perturb the Fourier spectrum of domain traces and discuss ways to identify the number of modes that yield reliable line tension information.