人类乳铁蛋白的结构重组n端叶2.0决议。
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天CL,安德森BF, Tweedie JW,贝克
人类乳铁蛋白的结构重组n端叶2.0决议。
J杂志。1993年8月20日,232 (4):1084 - 100。
- PubMed ID
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8371268 (在PubMed]
- 文摘
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人类乳铁蛋白的三维结构的n端half-molecule, LfN,由DNA重组方法,一直是由x射线晶体学2.0一项决议。蛋白质的铁箍,deglycosylated形式。x射线衍射数据获得的衍射测量分辨率3.2和同步数据采集,利用韦森伯摄影与成像板,1.8一项决议。分子结构是解决更换,使用本机的N-lobe diferric人类乳铁蛋白(Lf)搜索模型。必威国际app约束最小二乘优化程序(TNT)导致了模型结构的r因子0.184 34180年所有数据(反射)决议范围8.0 - 2.0。模型包括2490个蛋白质原子(残留4至327年),1 Fe3 + 1二氧化碳(2 -)和180溶剂分子,所有被认为是水。LfN的结构本质上是一样的N-lobe完整的低频,被折成两个相似的α/β域,Fe3 +和二氧化碳(2 -)绑定在一个特定的网站interdomain间隙。这些细节是不受deglycosylation或表达式在非系统。在C末端,然而,残留321到333的构象发生了变化。而在低频残留321年到332年之间形成一个螺旋交叉领域的铁网站,在LfN残留321年到326年有一个扩展的构象,形成第三个interdomain beta-strand,和残留328年到333年出现无序。 The conformational change is attributed to the loss of stabilizing interactions from the C-lobe and is mediated by two Gly residues, at positions 321 and 323. It is further proposed that the conformational change is responsible for the more facile iron release properties of LfN, by its effect on the hinge mechanism and increased solvent exposure of residues near the back of the iron site. Other details of the polypeptide chain conformation and the binding site have also been analysed. Two cis-proline residues are found at positions 71 and 142. The bidentate binding of the CO3(2-) to the metal ion is unambiguous, and a network of hydrogen bonds in and around the binding site links the two domains. Clearly-defined amino-aromatic hydrogen bonds are found for Arg210, near the metal site, and some 31 internal water molecules have been identified, 15 of them in essentially discrete sites, and 16 in a cluster filling a cavity in the interdomain cleft.