Darley-Usmar V M, Kennaway N G, Buist N R, Capaldi R A
Proc Natl Acad Sci U S A. 1983 Aug;80(16):5103-6. doi: 10.1073/pnas.80.16.5103.
The skeletal muscle of a patient with a mitochondrial myopathy was examined. A defect in the electron transport chain was identified at the position of complex III by activity measurements and the low levels of reducible cytochrome b. The polypeptide composition of complex III in the patient's mitochondria was determined by antibody binding experiments. The method allowed detection of individual polypeptides at a lower limit of 10-40 ng of protein. Characterization of protein composition is thus possible by using a biopsy sample of 1 g of tissue. The level of core proteins, FeS protein, and subunit VI was greatly diminished in the patient's mitochondria. Cytochrome c1 polypeptide was found at normal levels but was sensitive to proteolysis by trypsin. These results show that complex III is not assembled in the patient's mitochondria. The possible role of cytochrome b as the site of the primary lesion is discussed.
对一名线粒体肌病患者的骨骼肌进行了检查。通过活性测量和可还原细胞色素b的低水平，在复合体III的位置鉴定出电子传递链存在缺陷。通过抗体结合实验确定了患者线粒体中复合体III的多肽组成。该方法能够检测低至10 - 40 ng蛋白质的单个多肽。因此，使用1 g组织的活检样本就可以对蛋白质组成进行表征。患者线粒体中核心蛋白、铁硫蛋白和亚基VI的水平大幅降低。细胞色素c1多肽水平正常，但对胰蛋白酶的蛋白水解敏感。这些结果表明复合体III在患者线粒体中未组装。文中讨论了细胞色素b作为原发性病变位点的可能作用。
