MgATP对氯仿释放的线粒体腺苷三磷酸酶的腺苷三磷酸酶活性的抑制作用。

MgATP-induced inhibition of the adenosine triphosphatase activity of the chloroform-released mitochondrial adenosine triphosphatase.

Lowe P N, Beechey R B

Biochem J. 1981 May 15;196(2):433-42. doi: 10.1042/bj1960433.

Abstract

Preincubation of the ox heart chloroform-released mitochondrial ATPase with MgATP results in a time-dependent inhibition of ATPase activity. No re-activation occurs when MgATP remains in the preincubation medium. The enzyme activity returns when all the MgATP in the preincubation system has been hydrolysed. 2. The mechanism of the MgATP-induced inhibition was examined. Inhibition occurs on incubation with MgATP or other hydrolysable nucleotides. Incubation with MgADP or Pi does not cause any inhibition. Neither freshly bound adenine nucleotide nor Pi is associated with inhibited enzyme. The rate of MgATP-induced inhibition correlates with the rate of ATP hydrolysis in the preincubation medium. Changing the rate of ATP hydrolysis at a fixed concentration of ATP also changes the rate of MgATP-induced inhibition by the same proportion. The inhibition is thus related to the ATP-hydrolysis process itself. 3. We propose that intermediate enzyme species of the ATP-hydrolytic sequence can undergo a conformational change to form inhibited species. The kinetics of the inhibition suggest that a substrate-activation step is involved in ATP hydrolysis and MgATP-induced inhibition. 4. The effects of the nature of the preincubation medium on the process of MgATP-induced inhibition and its reversal were examined.

摘要

将牛心氯仿释放的线粒体ATP酶与MgATP预孵育会导致ATP酶活性随时间受到抑制。当MgATP保留在预孵育培养基中时，不会发生再激活。当预孵育系统中的所有MgATP都被水解时，酶活性恢复。2. 研究了MgATP诱导抑制的机制。与MgATP或其他可水解核苷酸孵育时会发生抑制。与MgADP或Pi孵育不会引起任何抑制。新结合的腺嘌呤核苷酸和Pi都与受抑制的酶无关。MgATP诱导抑制的速率与预孵育培养基中ATP水解的速率相关。在固定浓度的ATP下改变ATP水解的速率也会以相同比例改变MgATP诱导抑制的速率。因此，这种抑制与ATP水解过程本身有关。3. 我们提出，ATP水解序列的中间酶种类可以发生构象变化以形成受抑制的种类。抑制的动力学表明，底物激活步骤参与了ATP水解和MgATP诱导的抑制。4. 研究了预孵育培养基的性质对MgATP诱导抑制过程及其逆转的影响。