FLUX RATIO AND DRIVING FORCES IN A MODEL OF ACTIVE TRANSPORT
FLUX RATIO AND DRIVING FORCES IN A MODEL OF ACTIVE TRANSPORT
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DOI：
10.1016/s0006-3495(69)86395-2
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发表时间：
1969-01-01
影响因子：
3.4
通讯作者：
KEDEM, O
中科院分区：
文献类型：
--
作者：
BLUMENTHAL, R;KEDEM, O
为了分析主动运输的能量学，考虑了一个假设的载体模型，其中主动运输过程被减少到最少数量的基本步骤。检查以下三个量之间的关系：驱动主动运输的反应的亲和力、相同溶液之间的同位素通量比率（“短路”）以及主动运输系统可以维持的最大化学势差。同位素相互作用的相互依赖性以及运输和化学反应之间的耦合程度被明确地显示出来：当运输和化学反应完全耦合时，存在明显的同位素相互作用。一般来说，短路磁通比的对数（乘以RT）与最大化学势不相等。当代谢和运输之间的耦合非常松散时，或者当反应步骤比吸附的溶质穿过屏障的转移快得多时，这两个量大致相等。如果事先不知道载体的动力学参数，则必须测量最大电势和代谢反应对溶质流量的依赖性，以便推导出驱动反应的亲和力。在同一系统中测量通量比将产生关于载体机制的独立信息。
In order to analyze the energetics of active transport, a hypothetical carrier model is considered in which the active transport process is reduced to a minimal number of elementary steps. The relation between the following three quantities is examined: The affinity of the reaction driving the active transport, the ratio of isotope fluxes between identical solutions ("short-circuit"), and the maximal chemical potential difference which the active transport system can maintain. The interdependence of isotopeinteraction and the degree of coupling between transport and chemical reaction is shown explicitly: when the transport and chemical reaction are completely coupled, there is marked isotope interaction. In general, the logarithm of the short-circuit flux ratio (multiplied byRT) and the maximal chemical potential are not equal. The two quantities are approximately equal, when coupling between metabolism and transport is very loose, or when the reaction step is much faster than the transfer of the adsorbed solute across the barrier. Without prior knowledge of the kinetic parameters of the carrier, the maximal potential and the dependence of the metabolic reaction on solute flow have to be measured in order to derive the affinity of the driving reaction. Measurement of the flux ratio in the same system will then yield independent information on the carrier mechanism.