Wiedemann F R, Kunz W S
Klinik für Neurologie, Universitätsklinikum der Otto-von-Guericke Universität Magdeburg, Germany.
FEBS Lett. 1998 Jan 23;422(1):33-5. doi: 10.1016/s0014-5793(97)01586-x.
The oxygen dependence of cytochrome c oxidase control on succinate oxidation was investigated in saponin-permeabilized muscle fibers and isolated mitochondria from mouse quadriceps muscle applying metabolic control analysis. For this cyanide titrations of the oxygen consumption in the presence of succinate+rotenone were performed at different oxygen concentrations in the medium. While with isolated mitochondria high flux control coefficients were detected only at oxygen concentrations close to the KM value of cytochrome c oxidase, with saponin-permeabilized fibers a significant increase of cytochrome c oxidase flux control was already observed below 130 microM oxygen. The result is in line with the high oxygen sensitivity of maximal respiration of saponin-permeabilized muscle fibers (P50 = 33 microM) caused most probably by oxygen diffusion gradients through the fiber lattice. The oxygen dependence of cytochrome c oxidase flux control in muscle fibers can explain the pathological phenotype of mild cytochrome c oxidase deficiencies in mitochondrial myopathies.
运用代谢控制分析方法，研究了皂素通透化肌纤维和从小鼠股四头肌分离的线粒体中，细胞色素c氧化酶对琥珀酸氧化的氧依赖性。为此，在不同的介质氧浓度下，对琥珀酸+鱼藤酮存在时的氧消耗进行了氰化物滴定。对于分离的线粒体，仅在接近细胞色素c氧化酶KM值的氧浓度下检测到高通量控制系数，而对于皂素通透化的纤维，在低于130微摩尔氧的情况下，已观察到细胞色素c氧化酶通量控制的显著增加。该结果与皂素通透化肌纤维最大呼吸的高氧敏感性（P50 = 33微摩尔）一致，这很可能是由氧通过纤维晶格的扩散梯度引起的。肌纤维中细胞色素c氧化酶通量控制的氧依赖性可以解释线粒体肌病中轻度细胞色素c氧化酶缺陷的病理表型。
