Mathies Guinevere, Gast Peter, Chasteen N Dennis, Luck Ashley N, Mason Anne B, Groenen Edgar J J
Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands,
J Biol Inorg Chem. 2015 Apr;20(3):487-96. doi: 10.1007/s00775-014-1229-z. Epub 2014 Dec 24.
We report 275 GHz EPR spectra of human serum transferrin. At this high microwave frequency the zero-field splitting between the magnetic sublevels of the high-spin [Formula: see text] sites can be accurately determined. We find the zero-field splitting to be a sensitive probe of the structure of the transferrin iron-binding sites. Signals arising from iron bound to the transferrin N-lobe can clearly be distinguished from signals from iron bound to the C-lobe. Moreover, our spectra show that the structure of the iron site in the N-lobe is influenced by the presence and conformation of the C-lobe. The spectra of a series of N-lobe mutants altering the second-shell interaction of Arg124 with the synergistic anion carbonate reflect conformational changes induced at the iron site.
我们报道了人血清转铁蛋白的275 GHz电子顺磁共振（EPR）光谱。在这个高微波频率下，可以准确测定高自旋[公式：见正文]位点磁亚能级之间的零场分裂。我们发现零场分裂是转铁蛋白铁结合位点结构的灵敏探针。与转铁蛋白N叶结合的铁产生的信号可以与与C叶结合的铁产生的信号清晰区分。此外，我们的光谱表明，N叶中铁位点的结构受C叶的存在和构象影响。一系列改变精氨酸124与协同阴离子碳酸根的第二壳层相互作用的N叶突变体的光谱反映了铁位点诱导的构象变化。
