Hopfer U
J Supramol Struct. 1977;7(1):1-13. doi: 10.1002/jss.400070102.
The kinetic parameters of the Na+-dependent glucose transport system have been determined in isolated membrane vesicles for D-glucose, Na+, and phlorhizin. The D-glucose flux measurements were carried out by the equilibrium exchange procedure at constant external and internal Na+ concentrations and zero potential. Equations were developed to extract information about Km and Vmax from uptake measurements into a vesicle population that is heterogeneous with respect to size (surface to volume ratio). The Km for D-glucose was 14 mM and independent of the Na+-concentration, while the Vmax was strongly Na+-dependent and increased 15-fold between 1 and 100 mM Na+. The Km of Na+ for activation of the Vmax was 18 mM. The calculated KI values for phlorhizin were 2.7 and 1.9 micrometer when determined under active and equilibrating D-glucose flux conditions, respectively.
已在分离的膜囊泡中测定了钠依赖性葡萄糖转运系统对D-葡萄糖、钠离子和根皮苷的动力学参数。D-葡萄糖通量的测量是通过平衡交换程序在恒定的外部和内部钠离子浓度以及零电位下进行的。已推导出一些方程，用于从对大小（表面积与体积比）不均一的囊泡群体的摄取测量中提取有关米氏常数（Km）和最大反应速度（Vmax）的信息。D-葡萄糖的Km为14 mM，且与钠离子浓度无关，而Vmax则强烈依赖于钠离子，在1至100 mM钠离子浓度之间增加了15倍。激活Vmax的钠离子的Km为18 mM。当在活性和平衡的D-葡萄糖通量条件下测定时，根皮苷的计算抑制常数（KI）值分别为2.7和1.9微米。
