ASYMMETRY OF FACILITATED TRANSFER SYSTEM FOR HEXOSES IN HUMAN RED-CELLS AD SIMPLE KINETICS OF A 2 COMPONENT MODEL
ASYMMETRY OF FACILITATED TRANSFER SYSTEM FOR HEXOSES IN HUMAN RED-CELLS AD SIMPLE KINETICS OF A 2 COMPONENT MODEL
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DOI：
10.1113/jphysiol.1973.sp010225
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发表时间：
1973-01-01
影响因子：
5.5
通讯作者：
WIDDAS, WF
中科院分区：
文献类型：
--
作者：
BAKER, GF;WIDDAS, WF
1. 4,6 - O -乙基- α - D -葡萄糖（乙基葡萄糖）被用来研究当试剂(i)在细胞内和（ii）在细胞外时对葡萄糖交换通量的竞争性抑制。在20毫米和16°C条件下，50%的葡萄糖交换抑制在内部需要200毫米的甲基葡萄糖，而在外部需要25-30毫米。测定了不同抑制剂/葡萄糖浓度比下的抑制作用，数据分析表明，乙基葡萄糖的半饱和常数是细胞内葡萄糖的6倍，而细胞外则是1.5倍。然而，分析表明，对葡萄糖的亲和力的不对称性约为10倍，这将使对乙基葡萄糖的不对称性为40倍。这种不对称性使得有必要考虑具有不同组分的糖在内外膜界面上的转移机制，并且已经开发了双组分系统的简单动力学并用于定量分析实验数据。简要讨论了其与简单移动载体动力学的异同和与最近一些模型的异同。
1. 4, 6‐O‐Ethylidene‐α‐D‐glucopyranose (ethylidene glucose) has been used to study the competitive inhibition of glucose exchange fluxes when the reagent was (i) inside the cells and (ii) on the outside.2. 50% inhibition of glucose exchange at 20 mMand 16° C required 200 mMethylidene glucose when on the inside in contrast to 25–30 mMwhen on the outside.3. The inhibitions at different inhibitor/glucose concentration ratios were measured and analysis of the data suggested that the half‐saturation constant for ethylidene glucose was 6 times that for glucose inside the cell as against 1·5 outside. The analysis, however, suggested an asymmetry in respect to the affinities for glucose of approximately ten‐fold and this would make the asymmetry towards ethylidene glucose forty‐fold.4. Such asymmetries make it necessary to consider a transfer mechanism for sugars with different components on the outer and inner membrane interfaces and simple kinetics for a two component system have been developed and used for analysing the experimental data quantitatively.5. The kinetic similarities to and difference from the kinetics of a simple mobile carrier and those of some more recent models are briefly discussed.