Glerum M, Robinson B H, Spratt C, Wilson J, Patrick D
Department of Paediatrics and Biochemistry, University of Toronto, Ontario, Canada.
Am J Hum Genet. 1987 Oct;41(4):584-93.
Cultured skin fibroblasts from a child with fatal lacticacidemia displayed an abnormally high lactate:pyruvate ratio of 77:1, compared with control values of 22:1-27:1. When protease-treated isolated mitochondria were used, activity of the respiratory-chain enzymes was found to be approximately 60% of normal, and adenosine triphosphate synthesis was found to be normal with all substrates tested. In mitochondria prepared by means of digitonin treatment, adenosine triphosphate synthesis was depressed with all substrates tested, suggesting a defect in the operation of the cytochrome oxidase complex. In disrupted whole cells from the patient, cytochrome oxidase activity was 56% of the activity in the control cell line with the lowest activity. In the presence of a twofold excess of oxidized cytochrome c, patient cells showed 31% of the activity in controls. Cytochrome oxidase activity in both sonicated whole-cell preparations and in sonicated mitochondria displayed abnormal kinetics with regard to the substrate-reduced cytochrome c, which was particularly evident in the presence of excess oxidized cytochrome c. We believe that kinetically abnormal cytochrome oxidase complex is responsible for the biochemical and clinical abnormalities present in this patient.
一名患有致命性乳酸性酸中毒的儿童的培养皮肤成纤维细胞显示，乳酸与丙酮酸的比例异常高，为77:1，而对照值为22:1至27:1。当使用经蛋白酶处理的分离线粒体时，发现呼吸链酶的活性约为正常水平的60%，并且在所有测试底物下三磷酸腺苷合成均正常。在用洋地黄皂苷处理制备的线粒体中，所有测试底物的三磷酸腺苷合成均受到抑制，提示细胞色素氧化酶复合体的运作存在缺陷。在患者破碎的全细胞中，细胞色素氧化酶活性是对照细胞系中活性最低的56%。在氧化型细胞色素c过量两倍的情况下，患者细胞的活性为对照细胞的31%。超声处理的全细胞制剂和超声处理的线粒体中的细胞色素氧化酶活性，在底物还原型细胞色素c方面均表现出异常动力学，在氧化型细胞色素c过量时尤为明显。我们认为，动力学异常的细胞色素氧化酶复合体是该患者出现生化和临床异常的原因。
