The refined structure of canavalin from jack bean in two crystal forms at 2.1 and 2.0 Å resolution
The refined structure of canavalin from jack bean in two crystal forms at 2.1 and 2.0 Å resolution
复制标题
DOI：
10.1107/s0907444900002237
复制
发表时间：
2000-04-01
影响因子：
2.2
通讯作者：
McPherson, A
中科院分区：
文献类型：
--
作者：
Ko, TP;Day, J;McPherson, A
刀豆蛋白的结构在空间群 P2(1)3 和 P6(3) 的立方和六方晶体中分别被细化至 2.1 和 2.0 埃分辨率。三重分子对称性表现为两种晶体的对称性，其中每个相同的亚单元都是不对称单元。刀豆蛋白亚基由两个非常相似的结构域组成，每个结构域均由具有瑞士卷拓扑结构的核心子结构域和包含螺旋的环子结构域组成。与菜豆蛋白相比，改进的刀豆蛋白模型解决了二级结构元件氨基酸记录的差异。刀豆蛋白的两个结构域中均存在Z链，并且在每个结构域的A链和B链之间的环中观察到新的螺旋。根据重复的豌豆球蛋白域对模型进行分析。鉴定出三个严格保守的残基，两个甘氨酸和一个脯氨酸。整个豌豆球蛋白分子之间的相似性大于刀豆球蛋白和菜豆蛋白的单独结构域之间的相似性，来自大豆的蔗糖结合蛋白（SBP）的同源建模显示出与豌豆球蛋白相似的亚基三聚体组装。
The structure of canavalin was refined to 2.1 and 2.0 Angstrom resolution in cubic and hexagonal crystals of space group P2(1)3 and P6(3), respectively. The threefold molecular symmetry is expressed in the symmetry of both crystals, where each identical subunit is an asymmetric unit. The canavalin subunit consists of two very similar domains, each comprised of a core subdomain having Swiss-roll topology with a loop subdomain that contains helices. The refined canavalin models resolved the discrepancy in amino-acid registers of the secondary-structural elements compared with phaseolin. The presence of strand Z in both domains of canavalin was confirmed and a new helix in the loop between strands A and B of each domain was observed. The models were analyzed in terms of the duplicated vicilin domains. Three strictly conserved residues, two glycines and a proline, were identified. The similarity between entire vicilin molecules is greater than that between separate domains of canavalin and phaseolin, Homology modeling of the sucrose-binding protein (SBP) from soybean showed a plausible trimeric assembly of subunits similar to that of vicilins.