Thomanek U F, Parak F, Formanek S, Kalvius G M
Biophys Struct Mech. 1977 Sep 28;3(3-4):207-27. doi: 10.1007/BF00535697.
The static magnetic susceptibilities of different ferric high spin and low spin compounds of myoglobin (Mb(H2O), Mb(H2O) frozen under high pressure, MbF, MbCN) were measured in the temperature region between 4.2 K and 130 K. Mössbauer absorption experiments on Mb(H2O) and MbF were performed at different temperatures between 4.2 K and 180 K and in small magnetizing fields H less than or equal to 1 kOe. The evaluation of our experimental data was performed with a Hamiltonian describing of 3d-configuration of the ferric iron by taking into account the Coulomb repulsion of the five electrons within the 3d-shell, the crystal electric field of C2v-symmetry, and the spine-orbit coupling. The Hamiltonian contains the splitting energies of the five antibonding d-orbitals (dxy, dx2, dy2, dx2-y2, dz2) as parameters. The values of these energies were obtained by a least squares fitting procedure using our magnetic susceptibility data together with the g-factors taken from the literature. In the case of MbF the energy difference between the two lowest Kramers doublets was also determined from present Mössbauer data. The results of the susceptibility and the Mössbauer data are in good agreement. The splitting energies of the 3d-orbitals can be correlated to the distances between the iron and its nearest neighbours. The different positions of the iron in the compounds investigated are discussed.
在4.2 K至130 K的温度范围内，测量了肌红蛋白（Mb(H₂O)、高压下冷冻的Mb(H₂O)、MbF、MbCN）的不同铁高自旋和低自旋化合物的静态磁化率。在4.2 K至180 K的不同温度下，以及在小于或等于1 kOe的小磁化场H中，对Mb(H₂O)和MbF进行了穆斯堡尔吸收实验。通过考虑3d壳层内五个电子的库仑排斥、C₂v对称的晶体电场和自旋-轨道耦合，用描述铁离子3d构型的哈密顿量对我们的实验数据进行了评估。哈密顿量包含五个反键d轨道（dxy、dx²、dy²、dx² - y²、dz²）的分裂能作为参数。这些能量值是通过最小二乘法拟合程序获得的，该程序使用了我们的磁化率数据以及从文献中获取的g因子。对于MbF，还根据当前的穆斯堡尔数据确定了两个最低克莱默斯双重态之间的能量差。磁化率和穆斯堡尔数据的结果吻合良好。3d轨道的分裂能可以与铁及其最近邻原子之间的距离相关联。讨论了所研究化合物中铁的不同位置。
