X-ray structure of recombinant horse L-chain apoferritin at 2.0 angstrom resolution: Implications for stability and function
X-ray structure of recombinant horse L-chain apoferritin at 2.0 angstrom resolution: Implications for stability and function
复制标题
DOI：
10.1007/s007750050143
复制
发表时间：
1997-06-01
影响因子：
3
通讯作者：
Crichton, RR
中科院分区：
文献类型：
--
作者：
Gallois, B;dEstaintot, BL;Crichton, RR
重组马L链(RL)脱脂铁蛋白的X射线结构，在2.0埃分辨率下求解，最终R因子为17.99%。证明该序列第93位的残基是一个脯氨酸，而不是亮氨酸。在早期的测序研究中发现，该结构与其他载脂蛋白结构同构，因此我们特别关注那些与蛋白质的稳定性和功能相关的结构特征。氢键和盐桥相互作用的分析表明，二聚体和四聚体是蛋白质壳层中最稳定的分子实体：这一结果证实了早期的生物物理实验，与其他脱铁蛋白相比，马RL脱铁蛋白在酸性pH值下解离成亚单位以及在氯化胍溶液中完成解离的稳定性得到了比较。这强调了盐桥在这个蛋白质家族的稳定性中所起的作用，马的RL载脂蛋白明显比马的脾铁蛋白对变性的抵抗力更强，而后者又比任何人的Rh载铁蛋白更具抵抗力，即使是那些恢复了盐桥的人也是如此。最后，这个结构测定不仅确定了L链脱铁蛋白中存在一个预先形成的口袋，而且在已知的能够与卟啉结合的位置上。而且还强调了位于这个卟啉结合口袋入口处的一簇谷氨酸(E53、E56、E57和E60)的特殊功能。
The X-ray structure of recombinant horse L-chain (rL) apoferritin, solved at 2.0 Angstrom resolution with a final R factor of 17.99 %. gives evidence that the residue at position 93 in the sequence is a proline and not a leucine. as found in earlier sequencing studies, The structure is isomorphous with other apoferritin structures, and we thus draw particular attention to those structural features which can be related to the stability and function of the protein. Analysis of hydrogen bonding and salt bridge interactions shows a that dimers and tetramers are the most stable molecular entities within the protein shell: a result confirming earlier biophysical experiments, The stability of horse rL apoferritin to both dissociation into subunits at acidic pH values and to complete unfolding in guanidine chloride solutions is compared with that of other apoferritins. This emphasizes the role played by the salt bridge in the stability of this protein family, The horse rL apoferritin is significantly more resistant to denaturation than horse spleen ferritin, which in turn is more resistant than any human rH apoferritins, even those for which a salt bridge is restored. Finally this structure determination not only establishes that a preformed pocket exists in L-chain apoferritin, at a site known to be able to bind porphyrin. but also underlines the particular function of a cluster of glutamic acids (E53, E56, E57 and E60) located at the entrance of this porphyrin-binding pocket.