催化位点占据揭示 F（1）-ATP 酶的化学机械偶联在催化过程中。
Chemo-mechanical coupling in F(1)-ATPase revealed by catalytic site occupancy during catalysis.
机构信息
Department of Physics, Faculty of Science and Engineering, Waseda University, Okubo, Shinjuku-ku, Tokyo, Japan.
出版信息
Biophys J. 2010 Apr 7;98(7):1227-36. doi: 10.1016/j.bpj.2009.11.050.
F(1)-ATPase is a rotary molecular motor in which the central gamma subunit rotates inside a cylinder made of alpha(3)beta(3) subunits. To clarify how ATP hydrolysis in three catalytic sites cooperate to drive rotation, we measured the site occupancy, the number of catalytic sites occupied by a nucleotide, while assessing the hydrolysis activity under identical conditions. The results show hitherto unsettled timings of ADP and phosphate releases: starting with ATP binding to a catalytic site at an ATP-waiting gamma angle defined as 0 degrees , phosphate is released at approximately 200 degrees , and ADP is released during quick rotation between 240 degrees and 320 degrees that is initiated by binding of a third ATP. The site occupancy remains two except for a brief moment after the ATP binding, but the third vacant site can bind a medium nucleotide weakly.
F(1)-ATP 酶是一种旋转分子马达，其中中央γ亚基在由α(3)β(3)亚基组成的圆柱体内部旋转。为了阐明三个催化位点中的 ATP 水解如何协同驱动旋转，我们在相同条件下测量了核苷酸占据的位点占有率，即催化位点被核苷酸占据的数量。结果表明，ADP 和磷酸盐的释放时间迄今尚未确定：从 ATP 在定义为 0 度的 ATP 等待γ角度结合到一个催化位点开始，磷酸盐大约在 200 度释放，ADP 在由第三个 ATP 结合引发的快速旋转期间在 240 度和 320 度之间释放，快速旋转是由第三个 ATP 结合引发的。除了 ATP 结合后的短暂瞬间外，位点占有率保持为 2，但第三个空位可以微弱地结合中等核苷酸。
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