REGULATION OF ATP HYDROLYSIS IN HEPATOMA-22A MITOCHONDRIA
REGULATION OF ATP HYDROLYSIS IN HEPATOMA-22A MITOCHONDRIA
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DOI：
10.1016/0003-9861(91)90087-y
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发表时间：
1991-05-01
影响因子：
3.9
通讯作者：
KHODJAEV, EY
中科院分区：
文献类型：
--
作者：
CHERNYAK, BV;DUKHOVICH, VF;KHODJAEV, EY
在用解偶联剂预先孵育肝癌22a完整线粒体后，观察到ATP水解率降低。这种影响既是由于ATP转运速率的降低，也是由于F0F1-ATPase的失活。前者是解偶联剂诱导的ADP外流的结果。在来自肝癌(但不是来自小鼠肝脏)的失能线粒体中，基质中腺嘌呤核苷酸的浓度通过对羧基苍术苷(CatR)不敏感的运输系统与介质浓度相平衡。在给予能量的肝癌线粒体中，观察到CATR不敏感的ADP积聚和添加的ATP的化学计量交换。解偶联剂诱导的ATPase活性失活与Δ\̄GMH+、pH和ATP值的依赖关系与天然蛋白抑制剂(IF1)对F0F1的影响一致。用去污剂Lubrol-WX破坏线粒体后，也观察到依赖于ATP和pH的酶失活。肝癌线粒体中几乎所有的F0F1都以非抑制性方式与IF1结合.在解偶联剂存在下，该复合体通过可逆的pH依赖和不可逆的ATP依赖过程转化为抑制性复合体。这一pH依赖的步骤可以被可能与IF 1上带负电荷的残基结合的锌和镉离子阻断，从而阻止它们的质子化和蛋白质向抑制性构象的转化。
A decrease in the rate of ATP hydrolysis was observed after preincubation of intact mitochondria from hepatoma 22 a with an uncoupler. This effect is due both to a decrease in the rate of ATP transport and to an inactivation of the F 0 F 1-ATPase. The former effect is shown to result from an uncoupler-induced ADP efflux. In deenergized mitochondria from hepatoma (but not from mice liver), the concentration of adenine nucleotides in the matrix equilibrates with the medium concentration via a carboxyatractyloside (CATR)-insensitive transport system. CATR-insensitive accumulation of medium ADP and stoichiometric exchange of added ATP are observed in energized hepatoma mitochondria. The dependence of the uncoupler-induced inactivation of ATPase activity on Δ\̄ gmH+, pH, and ATP is consistent with the effect being caused by the natural protein inhibitor (IF 1) of F 0 F 1. ATP-and pH-dependent inactivation of the enzyme is also observed after disruption of mitochondria with the detergent Lubrol-WX. Almost all F 0 F 1 in hepatoma mitochondria have IF 1 bound in a noninhibitory manner. In the presence of uncoupler, this complex converts, via a reversible pH-dependent and an irreversible ATP-dependent process, to an inhibitory complex. The pH-dependent step can be blocked by Zn 2+ and Cd 2+ ions which probably bind to negatively charged residues on IF 1, thereby preventing their protonation and conversion of the protein to an inhibitory conformation.