Conformational changes within the subunit b-dimer of the E. coli ATP synthase occur upon binding to the F(1) sector. ESR spectra of spin-labeled b at room temperature indicated a pivotal point in the b-structure at residue 62. Spectra of frozen b +/- F(1) and calculated interspin distances suggested that where contact between b (2) and F(1) occurs (above about residue 80), the structure of the dimer changes minimally. Between b-residues 33 and 64 inter-subunit distances in the F(1)-bound b-dimer were found to be too large to accommodate tightly coiled coil packing and therefore suggest a dissociation and disengagement of the dimer upon F(1)-binding. Mechanistic implications of this "bubble" formation in the tether domain of ATP synthase b ( 2 ) are discussed.

中文翻译：

---

大肠杆菌 ATP 合酶 b-二聚体与 F(1)-ATPase 结合后的构象变化。

大肠杆菌 ATP 合酶的亚基 b-二聚体内的构象变化发生在与 F(1) 部门结合后。自旋标记的 b 在室温下的 ESR 谱表明残基 62 处 b 结构中的一个关键点。冷冻 b +/- F(1) 的谱和计算的自旋间距离表明 b (2) 和 F( 1) 发生（大约在残基 80 以上），二聚体的结构变化最小。发现 F(1)-结合的 b-二聚体中的 b-残基 33 和 64 个亚基间距离太大而无法容纳紧密卷曲的卷曲包装，因此表明二聚体在 F(1)-上解离和脱离捆绑。讨论了 ATP 合酶 b (2) 的系链域中这种“气泡”形成的机制含义。