Banci L, Bertini I, Ferroni F, Rosato A
Department of Chemistry, University of Florence, Italy.
Eur J Biochem. 1997 Oct 1;249(1):270-9. doi: 10.1111/j.1432-1033.1997.t01-1-00270.x.
The solution structure of the major form of the reduced soluble fragment of rat microsomal cytochrome b5 has been solved through 1H-NMR spectroscopy. The protein contains 98 amino acids. Proton assignment was available for residues 1-94, except 90 [Guiles, R. D., Basus, V. J., Kuntz, I. D. & Waskell, L. (1992) Biochemistry 31, 11,365-11,375] and has been confirmed. From 1722 NOEs, of which 1203 were found to be meaningful, a family of 40 energy-minimized structures has been obtained with average backbone rmsd (for residues 5-89) of 0.078 +/- 0.018 nm and average target function of 0.0045 nm2, no distance violations being larger than 0.029 nm. The structure has been compared with the X-ray structure of the oxidized rat mitochondrial isoenzyme and with that of the highly similar bovine microsomal isoenzyme in the oxidized form. The analysis of the elements of secondary structure is instructive in terms of their stability and of their occurrence in related structures, and of the capability of NMR and X-ray spectroscopy to observe them. Some detailed structural variations are noticed among the solved structures of the various isoenzymes and between solid and solution. The structural features in solution of the residues proposed to be involved in protein-protein recognition are found to be largely conserved with respect to the solid state.
通过1H-NMR光谱法解析了大鼠微粒体细胞色素b5还原型可溶性片段主要形式的溶液结构。该蛋白质含有98个氨基酸。除第90位残基外，已完成了第1至94位残基的质子归属[Guiles, R. D., Basus, V. J., Kuntz, I. D. & Waskell, L. (1992) Biochemistry 31, 11,365 - 11,375]，且已得到证实。从1722个核Overhauser效应（NOEs）中，发现其中1203个是有意义的，由此获得了40个能量最小化结构的家族，其平均主链均方根偏差（对于第5至89位残基）为0.078±0.018 nm，平均目标函数为0.0045 nm2，没有距离违反大于0.029 nm的情况。已将该结构与氧化型大鼠线粒体同工酶的X射线结构以及氧化形式的高度相似的牛微粒体同工酶的结构进行了比较。二级结构元件的分析对于它们的稳定性、在相关结构中的出现情况以及NMR和X射线光谱观察它们的能力而言具有指导意义。在各种同工酶的已解析结构之间以及在固态和溶液状态之间发现了一些详细的结构差异。发现拟参与蛋白质-蛋白质识别的残基在溶液中的结构特征相对于固态在很大程度上是保守的。
