Phlorizin binding to isolated enterocytes: Membrane potential and sodium dependence
Phlorizin binding to isolated enterocytes: Membrane potential and sodium dependence
复制标题
根皮苷与分离的肠细胞结合：膜电位和钠依赖性
DOI：
--
复制
发表时间：
2005
影响因子：
2.4
通讯作者：
G. Kimmich
中科院分区：
文献类型：
--
作者：
D. Restrepo;G. Kimmich
本文研究了鸡离体肠上皮细胞与苯酞苷的结合。细胞ATP耗尽，允许离子梯度和膜电位的广泛操作（Δψ）。在稳定状态下测定苯酞素的结合。载体特异性的根际素结合被定义为d-葡萄糖（90 mM）抑制结合。特异性结合表现出简单的米夏埃尔动力学作为根草素的函数。表明存在单一的均匀结合位点。钠浓度和Δψ改变表观结合亲和力，但不能改变最大结合位点数。相反，钠浓度的激活曲线呈s形，饱和钠的最大结合位点数量依赖于苯酞素。苯并菌素的结合速率是Δψ和钠浓度相关的。解离依赖于钠浓度，但不依赖于Δψ。理论分析表明底物的结合顺序是随机的。此外，数据表明，苯并菌素/钠的化学计量比为2:1。Δψ依赖性可以用两个模型来解释：易位是Δψ-dependent步骤，自由载体是阴离子，或者钠结合是Δψ-dependent步骤。
SummaryPhlorizin binding is studied in isolated intestinal epithelial cells of the chick. Cells are ATP depleted to allow extensive manipulation of ionic gradients and membrane potential (Δψ). Phlorizin binding is assayed at steady state. Carrier specific phlorizin binding is defined asd-glucose (90 mM) inhibitable binding. Specific binding displays simple Michaelian kinetics as a function of phlorizin. indicating the presence of a single homogeneous binding site. Sodium concentrations and Δψ modify the apparent binding affinity but not the maximum number of binding sites. In contrast, the activation curve as a function of sodium concentrations is sigmoid and the apparent maximum number of binding sites at saturating sodium is phlorizin dependent. The rate of phlorizin association is both Δψ and sodium-concentration dependent. Dissociation is sodium-concentration dependent but not Δψ dependent. Theoretical analysis indicates binding order of substrates is random. In addition, data suggests that the phlorizin/sodium stoichiometry is 2:1. The Δψ dependence can be explained by two models: either translocation is the Δψ-dependent step and the free carrier is anionic, or sodium binding is the Δψ-dependent step.
二次主动转运的电化学驱动力：Na -H 交换和 Na - 葡萄糖共转运的能量学和动力学。
DOI：
--
发表时间：
1984
期刊：
Society of General Physiologists series
影响因子：
--
作者：
Aronson,PS
通讯作者：
Aronson,PS