Ecole Polytechnique Fédérale de Lausanne, Institut des Sciences et Ingénierie Chimiques, BCH, 1015 Lausanne, Switzerland.
J Am Chem Soc. 2012 Feb 8;134(5):2481-4. doi: 10.1021/ja210238g. Epub 2012 Jan 27.
Understanding how proteins function at the atomic level relies in part on a detailed characterization of their dynamics. Ubiquitin, a small single-domain protein, displays rich dynamic properties over a wide range of time scales. In particular, several regions of ubiquitin show the signature of chemical exchange, including the hydrophobic patch and the β4-α2 loop, which are both involved in many interactions. Here, we use multiple-quantum relaxation techniques to identify the extent of chemical exchange in ubiquitin. We employ our recently developed heteronuclear double resonance method to determine the time scales of motions that give rise to chemical exchange. Dispersion profiles are obtained for the backbone NH(N) pairs of several residues in the hydrophobic patch and the β4-α2 loop, as well as the C-terminus of helix α1. We show that a single time scale (ca. 50 μs) can be used to fit the data for most residues. Potential mechanisms for the propagation of motions and the possible extent of correlation of these motions are discussed.
理解蛋白质在原子水平上的功能部分依赖于对其动力学的详细描述。泛素是一种小的单结构域蛋白质，在很宽的时间尺度范围内表现出丰富的动态特性。特别是，泛素的几个区域显示出化学交换的特征，包括疏水区和β4-α2 环，这两个区域都参与了许多相互作用。在这里，我们使用多量子弛豫技术来确定泛素中化学交换的程度。我们采用最近开发的异核双共振方法来确定导致化学交换的运动时间尺度。我们获得了疏水区和β4-α2 环以及α1 螺旋 C 端的几个残基的骨架 NH（N）对的弥散曲线。我们表明，单个时间尺度（约 50 μs）可用于拟合大多数残基的数据。讨论了运动传播的潜在机制以及这些运动的相关性的可能程度。
