Orban J, Alexander P, Bryan P
Center for Advanced Research in Biotechnology, University of Maryland, Rockville 20850.
Biochemistry. 1992 Apr 14;31(14):3604-11. doi: 10.1021/bi00129a008.
Two-dimensional NMR spectroscopy has been used to obtain sequence-specific 1H NMR assignments for the IgG-binding B2-domain of streptococcal protein G. Secondary structure elements were identified from analysis of characteristic backbone-backbone NOE patterns and amide proton exchange data. The B2-domain contains a four-stranded beta-sheet region in which the two inner strands form a parallel beta-sheet with each other and antiparallel beta-sheets with the outer strands. The outer strands are connected via a 16-residue alpha-helix and short loops on both ends of the helix. The alpha-helix and beta-sheet structures contain well-defined polar and apolar sides, and numerous long-range NOEs from the apolar helix to apolar sheet regions were used to derive a model for the global fold of the B2-domain. While the overall fold is similar to that obtained for B1-type domains, differences in amide proton exchange rates and hydrophobic packing are observed.
二维核磁共振光谱已被用于获得链球菌蛋白G的IgG结合B2结构域的序列特异性1H NMR归属。通过分析特征性的主链-主链NOE模式和酰胺质子交换数据确定了二级结构元件。B2结构域包含一个四链β-折叠区域，其中两条内链相互形成平行β-折叠，并与外链形成反平行β-折叠。外链通过一个16个残基的α-螺旋和螺旋两端的短环相连。α-螺旋和β-折叠结构包含明确的极性和非极性面，并且利用从非极性螺旋到非极性折叠区域的大量长程NOE推导出B2结构域整体折叠的模型。虽然整体折叠与B1型结构域相似，但观察到酰胺质子交换率和疏水堆积存在差异。
