Honerkamp-Smith Aurelia R, Veatch Sarah L, Keller Sarah L
Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA.
Biochim Biophys Acta. 2009 Jan;1788(1):53-63. doi: 10.1016/j.bbamem.2008.09.010. Epub 2008 Oct 1.
Scaling laws associated with critical points have the power to greatly simplify our description of complex biophysical systems. We first review basic concepts and equations associated with critical phenomena for the general reader. We then apply these concepts to the specific biophysical system of lipid membranes. We recently reported that lipid membranes can contain composition fluctuations that behave in a manner consistent with the two-dimensional Ising universality class. Near the membrane's critical point, these fluctuations are micron-sized, clearly observable by fluorescence microscopy. At higher temperatures, above the critical point, we expect to find submicron fluctuations. In separate work, we have reported that plasma membranes isolated directly from cells exhibit the same Ising behavior as model membranes do. We review other models describing submicron lateral inhomogeneity in membranes, including microemulsions, nanodomains, and mean field critical fluctuations, and we describe experimental tests that may distinguish these models.
与临界点相关的标度律能够极大地简化我们对复杂生物物理系统的描述。我们首先为普通读者回顾与临界现象相关的基本概念和方程。然后我们将这些概念应用于脂质膜这一特定的生物物理系统。我们最近报道，脂质膜可能包含与二维伊辛普适类行为一致的成分涨落。在膜的临界点附近，这些涨落为微米级大小，通过荧光显微镜可清晰观察到。在高于临界点的较高温度下，我们预期会发现亚微米级涨落。在另一项工作中，我们报道直接从细胞中分离出的质膜表现出与模型膜相同的伊辛行为。我们回顾了描述膜中亚微米级横向不均匀性的其他模型，包括微乳液、纳米域和平均场临界涨落，并描述了可能区分这些模型的实验测试。
