Smith L J, Sutcliffe M J, Redfield C, Dobson C M
Oxford Centre for Molecular Sciences, University of Oxford, U.K.
J Mol Biol. 1993 Feb 20;229(4):930-44. doi: 10.1006/jmbi.1993.1097.
The structure of the 129-residue protein hen lysozyme has been determined in solution by two-dimensional 1H nuclear magnetic resonance methods. 1158 NOE distance restraints, and 68 phi and 24 chi 1 dihedral angle restraints were employed in conjunction with distance geometry and simulated annealing procedures. The overall C alpha root-mean-square deviation from the average for 16 calculated structures is 1.8(+/- 0.2) A, but excluding 14 residues in exposed disordered regions, this value reduces to 1.3(+/- 0.2) A. Regions of secondary structure, and the four alpha-helices in particular, are well defined (C alpha root-mean-square deviation 0.8(+/- 0.3) A for helices). The main-chain fold is closely similar to structures of the protein in the crystalline state. Furthermore, many of the internal side-chains are found in well-defined conformational states in the solution structures, and these correspond well with the conformational states found in the crystal. The general high level of definition of mainchain and many internal side-chains in the solution structures is reinforced by the results of an analysis of coupling constants and ring current shifts. Many side-chains on the surface, however, are highly disordered amongst the set of solution structures. In certain cases this disorder has been shown to be dynamic in origin by the examination of 3J alpha beta coupling constants.
通过二维¹H核磁共振方法，已在溶液中确定了由129个氨基酸残基组成的鸡卵清溶菌酶的结构。结合距离几何和模拟退火程序，使用了1158个NOE距离约束以及68个φ和24个χ₁二面角约束。对于16个计算结构，整体Cα与平均值的均方根偏差为1.8（±0.2）Å，但排除暴露的无序区域中的14个残基后，该值降至1.3（±0.2）Å。二级结构区域，特别是四个α螺旋，定义明确（螺旋的Cα均方根偏差为0.8（±0.3）Å）。主链折叠与该蛋白质在晶体状态下的结构非常相似。此外，在溶液结构中发现许多内部侧链处于明确的构象状态，并且这些与晶体中发现的构象状态非常吻合。耦合常数和环电流位移分析的结果加强了溶液结构中主链和许多内部侧链的总体高清晰度定义。然而，在一组溶液结构中，表面上的许多侧链高度无序。在某些情况下，通过检查³Jαβ耦合常数已表明这种无序源于动态变化。
