Spin-label electron paramagnetic resonance and differential scanning calorimetry studies of the interaction between mitochondrial cytochrome c oxidase and adenosine triphosphate synthase complex.
Spin-label electron paramagnetic resonance and differential scanning calorimetry studies of the interaction between mitochondrial cytochrome c oxidase and adenosine triphosphate synthase complex.
复制标题
自旋标记电子顺磁共振和差示扫描量热法研究线粒体细胞色素 C 氧化酶和三磷酸腺苷合酶复合物之间的相互作用。
作者：
Qiu,ZH;Yu,L;Yu,CA
俄克拉荷马州州立大学生物化学系，Stillwater，俄克拉荷马州74078接收日期：1991年8月13日;修订后的手稿接收日期：1991年11月15日摘要：研究了细胞色素c氧化酶复合物与三磷酸腺苷合酶（F，F0）复合物在纯化的细胞色素c氧化酶中的相互作用，分散状态和嵌入磷脂囊泡的差示扫描量热法和自旋标记电子顺磁共振研究。洗涤剂分散的细胞色素氧化酶和F [F] 0复合物经历吸热热变性。然而，当这些复合物嵌入磷脂囊泡中时，它们经历放热热变性。释放的能量被认为是由于磷脂的不饱和脂肪酰基与通过去除相互作用蛋白质形成的复合物的暴露区域之间的应变相互作用的崩溃。同时含有细胞色素氧化酶复合物和F_1F_0的蛋白-磷脂囊泡的热变性放热焓变小于由每个单独的电子转移复合物形成的蛋白-磷脂囊泡的热变性放热焓变。这表明细胞色素氧化酶复合物与膜中的F [F0]之间存在特异性相互作用。饱和转移EPR研究提供了这两种复合物之间相互作用的进一步证据，其中自旋标记的细胞色素氧化酶的旋转相关时间显着增加，当复合物与F^ o混合，然后嵌入磷脂囊泡中。从这些结果可以得出结论，至少一部分的细胞色素氧化酶和一部分的FjFq形成一个超大分子复合物的线粒体内膜。FjFq和泛喹啉-细胞色素c还原酶之间没有检测到这样的超大分子复合物。
Department of Biochemistry, Oklahoma State University, Stillwater, Oklahoma 74078 Received August 13, 1991; Revised Manuscript Received November 15, 1991 abstract: The interaction between cytochrome c oxidase complex and adenosine triphosphate synthase (F, F0) complex in the purified, dispersed state and embedded in phospholipid vesicles was studied by differential scanning calorimetry and by spin-label electron paramagnetic resonance. The detergent-dispersed cytochrome oxidase and F [F0 complexes undergo endothermic thermodenaturation. However, when these complexes are embedded in phospholipid vesicles, they undergo exothermic thermodenaturation. The energy released is believed to result from the collapse of a strained interaction between unsaturated fatty acyl groups of phospholipids and an exposed area of the complex formed by the removal of interacting proteins. The exothermic enthalpy change of thermodenaturation of a protein-phospholipid vesicle containing both cytochrome oxidase complex and F] F0 was smaller than thatof a mixture of protein-phospholipid vesicles formed from each individual electron transfercomplex. This suggests specific interaction between cytochrome oxidase complex and F [F0 in the membrane. Further evidence for interaction between these two complexes is provided by saturation transfer EPR studies in which the rotational correlation time of spin-labeled cytochrome oxidase increases significantly when the complex is mixed with F^ o prior to being embedded in phospholipid vesicles. From these results, it is concluded that at least a part of cytochromeoxidase and a part of FjFq form a supermacromolecular complex in the inner mitochondrial membrane. No such supermacromolecular complex is detected between FjFq and ubiquinol-cytochrome c reductase.