Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (UK).
Chembiochem. 2013 Sep 23;14(14):1780-8. doi: 10.1002/cbic.201300193. Epub 2013 Jun 25.
(15) N NMR relaxation studies, analyses of NMR data to include chemical shifts, residual dipolar couplings (RDC), NOEs and H(N) -H(α) coupling constants, and molecular dynamics (MD) simulations have been used to characterise the behaviour of lysozyme from bacteriophage lambda (λ lysozyme) in solution. The lower and upper lip regions in λ lysozyme (residues 51-60 and 128-141, respectively) show reduced (1) H-(15) N order parameters indicating mobility on a picosecond timescale. In addition, residues in the lower and upper lips also show exchange contributions to T2 indicative of slower timescale motions. The chemical shift, RDC, coupling constant and NOE data for λ lysozyme indicate that two fluctuating β-strands (β3 and β4) are populated in the lower lip region while the N terminus of helix α6 (residues 136-139) forms dynamic helical turns in the upper lip region. This behaviour is confirmed by MD simulations that show hydrogen bonds, indicative of the β-sheet and helical secondary structure in the lip regions, with populations of 40-60 %. Thus in solution λ lysozyme adopts a conformational ensemble that will contain both the open and closed forms observed in the crystal structures of the protein.
（15）N NMR 弛豫研究、NMR 数据分析（包括化学位移、残差偶极耦合（RDC）、NOE 和 H（N）-H（α）耦合常数）和分子动力学（MD）模拟已被用于表征噬菌体 lambda（λ 溶菌酶）在溶液中的行为。λ 溶菌酶的下唇区（残基 51-60）和上唇区（残基 128-141）的（1）H-（15）N 顺序参数降低，表明在皮秒时间尺度上的运动性。此外，下唇区和上唇区的残基也显示出 T2 的交换贡献，表明存在较慢时间尺度的运动。λ 溶菌酶的化学位移、RDC、耦合常数和 NOE 数据表明，两个波动的 β-链（β3 和 β4）存在于下唇区，而螺旋 α6 的 N 端（残基 136-139）在上唇区形成动态的螺旋环。这一行为通过 MD 模拟得到证实，模拟显示氢键，表明在唇部区域存在 β-片层和螺旋二级结构，其丰度为 40-60%。因此，在溶液中，λ 溶菌酶采用的构象集合将包含在该蛋白晶体结构中观察到的开放和闭合形式。
