Maeda Y
Adv Biophys. 1978;11:199-213.
On the basis of experimental Mössbauer evidence, the electronic structures of heme iron are discussed for Mb and Hb. In the deoxygenated state, it is concluded from the electric field gradient tensor and the temperature dependence of the quadrupole splitting that the ferrous iron is not in the tetragonal ligand field with the symmetry axis perpendicular to the heme. The experimental results are well explained solely by rhombic perturbation. The electronic ground state is a component of the 5E term, and the principal axis of the anisotrophy is parallel to the heme plane. In the oxygenated state, there is no decisive conclusion on the bonding structure of the O2 molecule to the heme. Still, the two models of Pauling and Griffith are consistent with experimental results. Considering a relaxation between two possible conformational states, the peculiar temperature dependence of the quadrupole splitting is resolved in Fe-O2 model compounds.
基于实验性穆斯堡尔证据，讨论了肌红蛋白（Mb）和血红蛋白（Hb）中血红素铁的电子结构。在脱氧状态下，根据电场梯度张量和四极分裂的温度依赖性得出结论，亚铁离子不在对称轴垂直于血红素的四方配体场中。实验结果仅通过菱形微扰就能得到很好的解释。电子基态是5E项的一个分量，各向异性的主轴与血红素平面平行。在氧化状态下，关于O2分子与血红素的键合结构尚无定论。不过，鲍林和格里菲斯的两种模型与实验结果一致。考虑到两种可能构象状态之间的弛豫，在Fe - O2模型化合物中解决了四极分裂独特的温度依赖性问题。
