Requimte-CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus Caparica, 2829-516, Caparica, Portugal.
Dalton Trans. 2011 Dec 21;40(47):12713-8. doi: 10.1039/c1dt10975h. Epub 2011 Oct 20.
Geobacter sulfurreducens is a sediment bacterium that contains a large number of multiheme cytochromes. The family of five c(7) triheme periplasmic cytochromes from Geobacter sulfurreducens shows structural diversity of the heme core. Structural characterization of the relative orientation of the axial ligands of these proteins by (13)C-paramagnetic NMR was carried out. The structures in solution were compared with those obtained by X-ray crystallography. For some hemes significant differences exist between the two methods such that orientation of the magnetic axes obtained from NMR data and the orientation taken from the X-ray coordinates differ. The results allowed the orientation of the magnetic axes to be defined confidently with respect to the heme frame in solution, a necessary step for the use of paramagnetic constraints to improve the complete solution structure of these proteins.
脱硫杆菌是一种沉积物细菌，它含有大量多血红素细胞色素。从脱硫杆菌中分离出的五个 c(7) 三血红素周质细胞色素家族显示出血红素核心的结构多样性。通过 (13)C 顺磁 NMR 对这些蛋白质轴向配体的相对取向进行了结构表征。通过 X 射线晶体学比较了溶液中的结构。对于一些血红素，两种方法之间存在显著差异，以至于从 NMR 数据获得的磁轴取向与从 X 射线坐标获得的取向不同。结果允许相对于溶液中的血红素框架自信地定义磁轴的取向，这是使用顺磁约束来改善这些蛋白质完整溶液结构的必要步骤。
