Huang W, Dolmer K, Liao X, Gettins P G
Department of Biochemistry and Molecular Biology, College of Medicine, University of Illinois at Chicago 60612-4316, USA.
Protein Sci. 1998 Dec;7(12):2602-12. doi: 10.1002/pro.5560071214.
To better understand the structural basis for the binding of proteinase-transformed human alpha2-macroglobulin (alpha2M) to its receptor, we have used three-dimensional multinuclear NMR spectroscopy to determine the secondary structure of the receptor binding domain (RBD) of human alpha2M. Assignment of the backbone NMR resonances of RBD was made using 13C/15-N and 15N-enriched RBD expressed in Escherichia coli. The secondary structure of RBD was determined using 1H and 13C chemical shift indices and inter- and intrachain nuclear Overhauser enhancements. The secondary structure consists of eight strands in beta-conformation and one alpha-helix, which together comprise 44% of the protein. The beta-strands form three regions of antiparallel beta-sheet. The two lysines previously identified as being critical for receptor binding are located in (Lys1374), and immediately adjacent to (Lys1370) the alpha-helix, which also contains an (Arg1378). Secondary structure predictions of other alpha-macroglobulins show the conservation of this alpha-helix and suggest an important role for this helix and for basic residues within it for receptor binding.
为了更好地理解蛋白酶转化的人α2-巨球蛋白（α2M）与其受体结合的结构基础，我们使用三维多核核磁共振光谱来确定人α2M受体结合域（RBD）的二级结构。RBD的主链核磁共振共振归属是利用在大肠杆菌中表达的13C/15N和15N富集的RBD完成的。RBD的二级结构是通过1H和13C化学位移指数以及链间和链内核Overhauser效应来确定的。二级结构由八个β构象的链和一个α螺旋组成，它们共同构成了该蛋白质的44%。β链形成了三个反平行β折叠区域。先前确定对受体结合至关重要的两个赖氨酸位于（Lys1374），并且紧邻α螺旋（Lys1370），α螺旋中还含有一个（Arg1378）。其他α-巨球蛋白的二级结构预测显示该α螺旋具有保守性，并表明该螺旋及其内部的碱性残基在受体结合中起重要作用。
