Wagner R, Engelbrecht S, Andreo C S
Eur J Biochem. 1985 Feb 15;147(1):163-70. doi: 10.1111/j.1432-1033.1985.tb08732.x.
The hydrodynamic properties of isolated ATPases were studied via their rotational diffusion in buffer solution. Chloroplast F1-ATPase (CF1) and Escherichia coli F1-ATPase (EF1) were covalently labeled with eosinisothiocyanate and then investigated by polarized laser spectroscopy. The rotational correlation time in aqueous buffer of latent (five-subunit) CF1 was 390 ns. Four-subunit (delta-deficient) CF1 showed the same correlation time, however, for three-subunit (delta, epsilon-deficient) CF1 the rotational correlation time was more than eight times larger (3200 ns). The rotational correlation time of activated CF1 was three times larger than the one of latent CF1. These large changes in the rotational correlation times are directly related to changes in the quaternary structure of CF1 upon activation. EF1 was found to behave essentially as activated CF1. Based on the observed rotational correlation times we concluded that the mass distributions of latent CF1 and of delta-deficient CF1 resemble a dimeric arrangement. The structure of delta, epsilon-deficient CF1 more likely resembles a hexagon, the mass centers of the six main subunits lie in one plane. The structure of the activated forms of CF1 can be described best as an intermediate between the dimeric arrangement of latent CF1 and an octahedron. The large changes in the quaternary structure of isolated CF1 are reversed when the activation of the enzyme is reversed.
通过研究分离出的ATP酶在缓冲溶液中的旋转扩散，对其流体动力学性质进行了研究。用异硫氰酸伊红对叶绿体F1 - ATP酶（CF1）和大肠杆菌F1 - ATP酶（EF1）进行共价标记，然后用偏振激光光谱法进行研究。潜在的（五亚基）CF1在水性缓冲液中的旋转相关时间为390纳秒。四亚基（缺乏δ亚基）的CF1显示出相同的相关时间，然而，对于三亚基（缺乏δ和ε亚基）的CF1，旋转相关时间则超过其八倍（3200纳秒）。活化的CF1的旋转相关时间比潜在的CF1大三倍。旋转相关时间的这些巨大变化与CF1活化后四级结构的变化直接相关。发现EF1的行为与活化的CF1基本相同。基于观察到的旋转相关时间，我们得出结论，潜在的CF1和缺乏δ亚基的CF1的质量分布类似于二聚体排列。缺乏δ和ε亚基的CF1的结构更可能类似于六边形，六个主要亚基的质心位于同一平面。CF1活化形式的结构最好描述为潜在CF1的二聚体排列和八面体之间的中间结构。当酶的活化被逆转时，分离出的CF1的四级结构的巨大变化也会逆转。
