Davis E J, Davis-Van Thienen W I
Arch Biochem Biophys. 1984 Sep;233(2):573-81. doi: 10.1016/0003-9861(84)90481-8.
Liver mitochondria provided with an oxidizable substrate, ATP, oxygen, and an ADP-generating system (soluble F1-ATPase) were used to reevaluate the rate-controlling step(s) intrinsic to all of the processes of mitochondrial oxidative phosphorylation. The quantity termed "control strength" (C), previously defined as the fractional change in flux through a (system) induced by a fractional change in the concentration of an individual enzyme in the system, has been used to evaluate rate-influencing steps in this overall process by carefully defining the dimensions of the "system" under analysis. If the system is defined by a suspension of mitochondria provided with substrates, plus an extrinsic ADP-generating process (ATPase), the value of C of the latter for the overall process of phosphorylation-linked respiration is near 1.0 until the capacity of the mitochondria to phosphorylate ADP is approached, after which C for the soluble ATPase becomes zero as the maximum capacity for phosphorylation is attained. Carboxyatractyloside was found only marginally to inhibit respiration stimulated by ATPase, even when a large percentage of adenine nucleotide translocase molecules were immobilized. The relative lack of effect of carboxyatractyloside on phosphorylating respiration is explained by the readjustment of the concentration of one of the substrates (ADP) and an inhibitor (ATP), which results from inhibition of adenine nucleotide translocase. The residual blunted inhibition of respiration is explained by product inhibition of the ADP-regenerating ATPase, and not necessarily to any intrinsically mitochondrial intermediate process. The system being evaluated can be redefined to include only the processes intrinsic to mitochondria. This can be achieved by providing exactly comparable substrate concentrations to the mitochondria under comparable incubation conditions. Under these conditions, the adenine nucleotide translocase is the principal, if not the only, rate-controlling step in the overall process of oxidative phosphorylation until a new rate-limitation is attained (ATP synthesis). These data are consistent with the conclusion that, at intermediate rates of phosphorylation-coupled respiration, the extramitochondrial ATP/ADP ratio regulates this process through its kinetic effects on the catalytic properties of the adenine nucleotide translocase.
利用含有可氧化底物、ATP、氧气以及ADP生成系统（可溶性F1 - ATP酶）的肝脏线粒体，重新评估线粒体氧化磷酸化所有过程固有的速率控制步骤。之前定义的“控制强度”（C），即系统中单个酶浓度的分数变化所引起的通过该（系统）通量的分数变化，已通过仔细定义所分析“系统”的维度，用于评估这一整体过程中的速率影响步骤。如果系统由含有底物的线粒体悬浮液加上外部ADP生成过程（ATP酶）定义，那么在接近线粒体磷酸化ADP的能力之前，后者对于磷酸化偶联呼吸的整体过程的C值接近1.0，之后随着达到最大磷酸化能力，可溶性ATP酶的C值变为零。发现羧基苍术苷仅对ATP酶刺激的呼吸有轻微抑制作用，即使很大比例的腺嘌呤核苷酸转位酶分子被固定。羧基苍术苷对磷酸化呼吸作用影响相对较小，这是由于腺嘌呤核苷酸转位酶受到抑制后，一种底物（ADP）和一种抑制剂（ATP）浓度的重新调整所致。呼吸作用残留的微弱抑制是由ADP再生ATP酶的产物抑制所解释，而不一定是任何线粒体内在的中间过程。所评估的系统可以重新定义为仅包括线粒体内固有的过程。这可以通过在可比的孵育条件下为线粒体提供完全可比的底物浓度来实现。在这些条件下，腺嘌呤核苷酸转位酶是氧化磷酸化整体过程中主要的（如果不是唯一的）速率控制步骤，直到达到新的速率限制（ATP合成）。这些数据与以下结论一致：在磷酸化偶联呼吸的中间速率下，线粒体外的ATP/ADP比值通过其对腺嘌呤核苷酸转位酶催化特性的动力学效应来调节这一过程。
