Carnitine-acylcarnitine translocase catalyzes an equilibrating unidirectional transport as well.
Carnitine-acylcarnitine translocase catalyzes an equilibrating unidirectional transport as well.
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肉碱-酰基肉碱转位酶也催化平衡单向运输。
DOI：
10.1016/s0021-9258(19)85841-6
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
R. Parvin
中科院分区：
文献类型：
--
作者：
S. Pande;R. Parvin
除了肉碱-酰基肉碱转位酶催化的交换扩散之外，肉碱相对较慢的单向转运也在线粒体中进行。后者沿着肉碱浓度梯度的方向进行，并导致跨内膜的肉碱浓度平衡。催化交换扩散的相同易位酶似乎催化单向运输，因为这两个过程表现出相似的底物特异性、对抑制剂的敏感性、高温度系数、对肉碱的明显亲和力以及缺乏能量需求。单向输入的肉碱很容易与中等肉碱交换，表明这两个运输过程共享相同的线粒体肉碱池。单向运输似乎在体内发挥作用；它的运作似乎不仅可以让线粒体获得肉碱，而且可以随着组织肉碱总浓度的变化来调整其更快的交换扩散反应的速率。研究发现，肉碱-酰基肉碱转位酶在大鼠肝脏线粒体中的活性约为心脏线粒体中的 15 倍。
Besides carnitine-acylcarnitine translocase-catalyzed exchange diffusions, a relatively much slower unidirectional transport of carnitines also proceeds in mitochondria. The latter proceeds in the direction of the concentration gradient of carnitines and leads to the equilibration of carnitine concentration across the inner membrane. The same translocase that catalyzes exchange diffusion appears to catalyze unidirectional transport inasmuch as the two processes showed similar substrate specificity, sensitivity to inhibitors, high temperature coefficients, apparent affinity for carnitine, and a lack of energy requirement. The unidirectionally imported carnitine readily exchanged against medium carnitine, indicating that the two transport processes share the same pool of mitochondrial carnitine. Unidirectional transport appears to be functional in vivo; its operation seems not only to allow mitochondria to acquire carnitine but to adjust the rates of their faster exchange-diffusion reactions with changes in total tissue carnitine concentrations. The carnitine-acylcarnitine translocase was found to be about 15 times as active in mitochondria of rat liver as in those of heart.