Potter K, Spencer R G, McFarland E W
Department of Chemical Engineering, University of California, Santa Barbara 93106-5080, USA.
Biochim Biophys Acta. 1997 Mar 15;1334(2-3):129-39. doi: 10.1016/s0304-4165(96)00083-9.
The diffusion of copper ions in bovine nasal cartilage (BNC), a dense connective tissue, was investigated to further the understanding of ion transport in charged biopolymer systems. Using an inversion-recovery null-point imaging technique, it was found that the diffusion rate of divalent copper ions into cartilage was significantly lower in normal BNC than in BNC in which the matrix fixed charges had been reduced by enzymatic digestion or acid neutralization. In normal cartilage, counterion diffusion was not well described by a simple Fickian process, likely owing to the high charge density of the constituent molecules. In contrast, in both digested and acid neutralized BNC, counterion diffusion appeared Fickian. Features of the ion transport process were modeled using a diffusion equation which included a linear sorption term to account for cation binding. The diffusion coefficient of copper in cartilage increased with decreasing matrix fixed charge and was constant for reservoir concentrations up to 30 mM. The activation energy for the diffusion of copper into BNC was determined to be 34.5 kJ/mol.
为了进一步了解带电生物聚合物系统中的离子运输，对铜离子在致密结缔组织——牛鼻软骨（BNC）中的扩散进行了研究。使用反转恢复零点成像技术发现，二价铜离子向软骨中的扩散速率在正常BNC中显著低于通过酶消化或酸中和降低了基质固定电荷的BNC。在正常软骨中，抗衡离子扩散不能用简单的菲克过程很好地描述，这可能是由于组成分子的高电荷密度所致。相比之下，在消化和酸中和的BNC中，抗衡离子扩散呈现出菲克扩散特征。使用包含线性吸附项以解释阳离子结合的扩散方程对离子运输过程的特征进行了建模。软骨中铜的扩散系数随着基质固定电荷的降低而增加，并且对于高达30 mM的储库浓度是恒定的。确定铜扩散到BNC中的活化能为34.5 kJ/mol。
