Deves R, Boyd C A
Department of Physiology and Biophysics, University of Chile, Santiago.
Proc R Soc Lond B Biol Sci. 1989 Jun 22;237(1286):85-97. doi: 10.1098/rspb.1989.0038.
A method is described that allows the determination of kinetic parameters for carrier-mediated transport of unlabelled compounds. The ability of these compounds to relieve the inhibition of labelled substrate efflux produced by addition of an external competitive inhibitor is studied. The method is of general applicability and does not depend upon any intrinsic asymmetry in the ratio of the rates of translocation of the loaded and unloaded carrier. In this paper it is used in a study of the human placental sulphate transporter. Experiments on brush-border membrane vesicles show the method to predict quantitatively kinetic parameters for unlabelled sulphate entry. Further analysis shows this carrier to have a broad specificity for other oxyanions (selenate, tung-state, molybdate and chromate) with the following selectivity sequence: for rate of translocation, SO4, SeO4 greater than WO4 greater than MoO4 much greater than CrO4; for binding affinity, CrO4 greater than MoO4, WO4 greater than SO4, SeO4.
本文描述了一种用于测定未标记化合物载体介导转运动力学参数的方法。研究了这些化合物解除因添加外部竞争性抑制剂而产生的标记底物外排抑制的能力。该方法具有普遍适用性，不依赖于加载和卸载载体转运速率比值中的任何内在不对称性。本文将其用于研究人胎盘硫酸盐转运体。对刷状缘膜囊泡的实验表明，该方法可定量预测未标记硫酸盐进入的动力学参数。进一步分析表明，该载体对其他含氧阴离子（硒酸盐、钨酸盐、钼酸盐和铬酸盐）具有广泛的特异性，其选择性顺序如下：就转运速率而言，SO4、SeO4＞WO4＞MoO4＞＞CrO4；就结合亲和力而言，CrO4＞MoO4，WO4＞SO4，SeO4。
