Haverkamp R G, Marshall A T, Williams M A K
Institute of Technology and Engineering, Massey University, Palmerston North 5331, New Zealand.
Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Feb;75(2 Pt 1):021907. doi: 10.1103/PhysRevE.75.021907. Epub 2007 Feb 15.
We derive an expression that represents the physical behavior of a polysaccharide molecule as it is stretched from the entropic region, through one or more ring conformational transformations, into the Hookean regime. The model adapts existing models in order to accommodate one or more force-induced conformational transformations of the glycan rings and is based on the concept of equilibrium between the clicked (longer conformers) and unclicked states. This equilibrium is determined by the Gibbs energy difference between these two states which is perturbed in favor of the clicked states by the force applied to the molecule. The derived expression is used to generate force-extension curves for model polymers and can illustrate the effect of the Gibbs energy for each transformation on the shape of these curves. It is also used to fit the force-extension curves of polysaccharides to obtain the Gibbs energy differences between the conformers. Good agreement was found between this model and experimental data on carboxymethylamylose, dextran, alginate, and pectin.
我们推导了一个表达式，该表达式描述了多糖分子从熵区域开始，经过一个或多个环构象转变，直至进入胡克区域时的物理行为。该模型对现有模型进行了调整，以适应聚糖环的一个或多个力诱导构象转变，并且基于点击（较长构象体）状态和未点击状态之间的平衡概念。这种平衡由这两种状态之间的吉布斯自由能差决定，施加在分子上的力会使平衡偏向点击状态。推导得到的表达式用于生成模型聚合物的力-伸长曲线，并可说明每次转变的吉布斯自由能对这些曲线形状的影响。它还用于拟合多糖的力-伸长曲线，以获得构象体之间的吉布斯自由能差。该模型与羧甲基直链淀粉、葡聚糖、藻酸盐和果胶的实验数据之间取得了良好的一致性。
