Schwalbe H, Grimshaw S B, Spencer A, Buck M, Boyd J, Dobson C M, Redfield C, Smith L J
Oxford Centre for Molecular Sciences, New Chemistry Laboratory, University of Oxford, Oxford OX1 3QT, England.
Protein Sci. 2001 Apr;10(4):677-88. doi: 10.1110/ps.43301.
A high resolution NMR structure of hen lysozyme has been determined using 209 residual 1H-15N dipolar coupling restraints from measurements made in two different dilute liquid crystalline phases (bicelles) in conjunction with a data set of 1632 NOE distance restraints, 110 torsion angle restraints, and 60 hydrogen bond restraints. The ensemble of 50 low-energy calculated structures has an average backbone RMSD of 0.50+/-0.13A to the mean structure and of 1.49+/-0.10A to the crystal structure of hen lysozyme. To assess the importance of the dipolar coupling data in the structure determination, the final structures are compared with an ensemble calculated using an identical protocol but excluding the dipolar coupling restraints. The comparison shows that structures calculated with the dipolar coupling data are more similar to the crystal structure than those calculated without, and have better stereochemical quality. The structures also show improved quality factors when compared with additional dipolar coupling data that were not included in the structure calculations, with orientation-dependent 15N chemical shift changes measured in the bicelle solutions, and with T1/T2 values obtained from 15N relaxation measurements. Analysis of the ensemble of NMR structures and comparisons with crystal structures, 15N relaxation data, and molecular dynamics simulations of hen lysozyme provides a detailed description of the solution structure of this protein and insights into its dynamical behavior.
利用在两种不同的稀液晶相（双分子层）中测得的209个残余1H-15N偶极耦合约束，结合1632个NOE距离约束、110个扭转角约束和60个氢键约束的数据集，确定了母鸡溶菌酶的高分辨率NMR结构。50个低能量计算结构的集合相对于平均结构的平均主链RMSD为0.50±0.13Å，相对于母鸡溶菌酶的晶体结构为1.49±0.10Å。为了评估偶极耦合数据在结构测定中的重要性，将最终结构与使用相同方案但排除偶极耦合约束计算得到的集合进行比较。比较表明，包含偶极耦合数据计算得到的结构比不包含该数据计算得到的结构更类似于晶体结构，并且具有更好的立体化学质量。与未包含在结构计算中的其他偶极耦合数据、在双分子层溶液中测得的与取向相关的15N化学位移变化以及从15N弛豫测量获得的T1/T2值相比，这些结构还显示出更好的质量因子。对NMR结构集合的分析以及与晶体结构、15N弛豫数据和母鸡溶菌酶分子动力学模拟的比较，提供了该蛋白质溶液结构的详细描述，并深入了解了其动力学行为。
