Timasheff Serge N
Biochemistry Department, MS 009, 415 South Street, Waltham, MA 02453-2728, USA.
Biophys Chem. 2002 Dec 10;101-102:99-111. doi: 10.1016/s0301-4622(02)00188-6.
An analysis of Schellman's treatment of preferential interactions is presented, as viewed by a laboratory practitioner of the art. Starting with an intuitive description of what binding is in terms of the distribution of molecules of water and of a weakly interacting ligand (co-solvent), Schellman proceeded to a rigorous thermodynamic definition in which he showed that classical, dialysis equilibrium, binding is a purely thermodynamic quantity. Putting water and the co-solvent on an equivalent footing, he showed that the classical binding treatment is inadequate for weakly interacting systems, in which the replacement of water by ligand and exclusion of co-solvent are symmetrical concepts. Analyzing specifically the simple model of a single independent site, Schellman demonstrated how a positive binding constant can give rise to a measured negative binding stoichiometry. He showed that the origin of the complicated binding isotherms is the non-idealities of water and co-solvent, and went further to analyze critically the effect of site heterogeneity on the ligand concentration dependencies of site occupancy, preferential binding and the thermodynamic quantities, enthalpy, entropy and Gibbs free energy. This exposition of the Schellman treatment is accompanied by illustrations drawn from the experimental results obtained in this author's laboratory.
本文呈现了一位实验室从业者对谢尔曼（Schellman）关于优先相互作用处理方法的分析。从对结合在水和弱相互作用配体（共溶剂）分子分布方面的直观描述开始，谢尔曼进而给出了一个严格的热力学定义，他证明了经典的透析平衡结合是一个纯粹的热力学量。他将水和共溶剂置于同等地位，表明经典的结合处理方法对于弱相互作用系统是不充分的，在这类系统中，配体取代水和共溶剂的排斥是对称的概念。通过具体分析单个独立位点的简单模型，谢尔曼展示了正的结合常数如何导致测得的负的结合化学计量比。他表明复杂结合等温线的起源是水和共溶剂的非理想性，并进一步批判性地分析了位点异质性对位点占有率、优先结合以及热力学量（焓、熵和吉布斯自由能）的配体浓度依赖性的影响。对谢尔曼处理方法的阐述配有取自作者实验室所获实验结果的插图。
