Cardiolipin-depleted bovine heart cytochrome c oxidase: binding stoichiometry and affinity for cardiolipin derivatives.
Cardiolipin-depleted bovine heart cytochrome c oxidase: binding stoichiometry and affinity for cardiolipin derivatives.
复制标题
心磷脂耗尽的牛心细胞色素 c 氧化酶：结合化学计量和对心磷脂衍生物的亲和力。
DOI：
10.1021/bi00490a012
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发表时间：
1990
期刊：
影响因子：
2.9
通讯作者：
Talbert,LH
中科院分区：
文献类型：
--
作者：
Robinson,NC;Zborowski,J;Talbert,LH
1990年5月3日收到的修订版Mandarin pt摘要：洗涤剂溶解的牛心细胞色素c氧化酶每摩尔单体复合物需要2摩尔紧密结合的心磷脂（CL）才能发挥功能活性。四条证据支持这一结论：（1）磷脂耗竭表明，两个紧密结合的CL必须保持与细胞色素c氧化酶的结合，以保持完整的电子传递活性。(2)两个紧密结合的CL的去除与通过2摩尔的外源性CL的再结合而恢复的降低的活性相关。(3)CL耗竭的细胞色素c氧化酶对2-[14 C]乙酰心磷脂（AcCL）有两个高亲和力结合位点，Xdapp< 0.1 μ mol/L，这两个结合位点在含有内源性CL的酶中不存在。另外2-3个较低亲和力的AcCL结合位点，Ad app= 4 μ g，存在于CL耗尽的复合物中，但这些位点也存在于含有内源性CL的酶中。(4)CL、单溶血心磷脂（MLCL）和二溶血心磷脂（DLCL）竞争AcCL结合，其相对亲和力与通过恢复电子传递活性测量的亲和力大致相同（MLCL竞争比DLCL好得多）。然而，当MLCL和DLCL与高亲和力位点结合时，它们在恢复最大活性方面的有效性仅为CL的60%和15%。CL、MLCL、DLCL及其一些酰化衍生物的结合特异性表明非极性尾部对于结合最重要，而非极性头部基团。CL、MLCL或DLCL中羟基的存在或不存在对结合亲和力也几乎没有影响。结合特异性明显有利于CL，因为磷脂酰甘油、磷脂酸和磷脂酰胆碱各自对CL结合位点具有非常低的亲和力（Xdap.> 20分）。因此，我们得出结论，恢复活动CL耗尽细胞色素c氧化酶是高度特异性的，需要重新关联的CL，或结构相似的化合物，具有两个高亲和力的结合位点。
Revised Manuscript Received May 3, 1990 abstract: Detergent-solubilized bovine heart cytochrome c oxidase requires 2 mol of tightly bound cardiolipin (CL) per mole of monomeric complex for functional activity. Four lines of evidence support this conclusion:(1) Phospholipid depletion shows that two tightly bound CL’s must remain associated with cytochrome c oxidase in order to maintain full electron transport activity.(2) Removal of the two tightly bound CL’s correlates with decreased activity that is restored by reassociation of 2 mol of exogenous CL.(3) CL-depleted cytochrome c oxidase has two high-affinity binding sites for 2-[14C] acetylcardiolipin (AcCL), Xdapp< 0.1 ĩ, that are not presentin enzyme containing endogenous CL. An additional 2-3 lower affinity AcCL binding sites, Ad app= 4 ĩ, are present in the CL-depleted complex, but these sites are also present in enzyme containing endogenous CL.(4) CL, monolysocardiolipin (MLCL), and dilysocardiolipin (DLCL) compete for AcCL binding with approximately the same relative affinities as those measured by the restoration of electron transport activity (MLCL competes much better than DLCL). However, MLCL and DLCL are only 60% and 15% as effective as CL in restoring maximum activity when they are bound to the high-affinity sites. The binding specificity of CL, MLCL, DLCL, and some of their acylated derivatives indicates that the apolar tails are most important for binding, not the polar head group. The presence or absence of hydroxyl groups in CL, MLCL, or DLCL also has little effect upon binding affinities. Binding specificity clearly favors CL since phosphatidylglycerol, phosphatidic acid, and phosphatidylcholine each have very low affinity for the CL binding sites(Xdap.> 20 ĩ). We, therefore, conclude that restoration of activity to CL-depleted cytochrome c oxidase is highly specific and requires the reassociation of CL, or structurally similar compounds, with two high-affinity binding sites.