Thomas N E, Coakley W T
School of Pure and Applied Biology, University of Wales, Cardiff.
Biophys J. 1995 Oct;69(4):1387-401. doi: 10.1016/S0006-3495(95)80008-1.
The topology of the contact seam of human erythrocytes adhered by dextran, an uncharged polymer, has been examined. Particular attention has been paid to the influence of electrostatic intermembrane interactions since their magnitude and range can be accurately estimated. Normal cells formed a continuous seam, whereas erythrocytes with pronase-modified glycocalices formed localized contact points on adhesion in 72 kDa dextran in buffered 145 mM NaCl. The dependence of the inter-contact distance lambda on dextran concentration [D] over the range 2-6% w/v, was given by lambda = C[D]-0.62, where C was a constant. The index of [D] was independent of dextran molecular mass over the range 20 to 450 kDa. The inter-contact distance for pronase-pretreated cells in 6% w/v 72 kDa dextran increased from 0.78 to 1.4 microns as [NaCl] was reduced through the range 145 to 90 mM and the suspending phase was maintained at isotonicity by using sorbitol to replace NaCl. The formation and lateral separation of the contact points are discussed from the perspective of linear interfacial instability theory. The theory allows a quantitative explanation for the experimentally observed dependence of inter-contact distance and of disturbance growth rate on change in electrostatic interaction. The results suggest that the dominant wavelength, determining the inter-contact distance, is established on approaching membranes when the layers of cell surface charge are separated by a perpendicular distance of < 14 nm (bilayer separation of 24 nm).
已对由不带电荷的聚合物葡聚糖粘附的人红细胞接触缝的拓扑结构进行了研究。由于静电膜间相互作用的大小和范围可以准确估计，因此对其影响给予了特别关注。正常细胞形成连续的缝，而用链霉蛋白酶修饰糖萼的红细胞在缓冲的145 mM NaCl中的72 kDa葡聚糖中粘附时形成局部接触点。在2-6% w/v范围内，接触间距λ对葡聚糖浓度[D]的依赖性由λ = C[D]-0.62给出，其中C为常数。在20至450 kDa范围内，[D]的指数与葡聚糖分子量无关。当[NaCl]从145 mM降低到90 mM，并用山梨醇替代NaCl使悬浮相保持等渗时，在6% w/v 72 kDa葡聚糖中经链霉蛋白酶预处理的细胞的接触间距从0.78增加到1.4微米。从线性界面不稳定性理论的角度讨论了接触点的形成和横向分离。该理论对实验观察到的接触间距和扰动生长速率对静电相互作用变化的依赖性给出了定量解释。结果表明，决定接触间距的主导波长是在细胞表面电荷层被垂直距离< 14 nm（双层间距为24 nm）分隔的接近膜时建立的。
