Roberts J E, Hoffman B M, Rutter R, Hager L P
J Biol Chem. 1981 Mar 10;256(5):2118-21.
Electron-nuclear double resonance spectra of horseradish peroxidase Compound I exhibit resonances from 14N and beta-protons, and most probably alpha-protons as well. The measurements prove that the oxyferryl iron of this enzymic intermediate is spin-coupled to a porphyrin radical. Comparison of experimentally obtained average pi-electron spin densities with theoretical predictions for a 4-fold symmetric porphyrin pi-cation radical is supportive of a 2A2u assignment for the radical's electronic state.
辣根过氧化物酶化合物I的电子-核双共振光谱显示出来自14N和β-质子的共振，很可能还有α-质子的共振。这些测量证明，这种酶中间体的氧合铁与卟啉自由基发生自旋耦合。将实验获得的平均π电子自旋密度与4重对称卟啉π-阳离子自由基的理论预测进行比较，支持了该自由基电子态的2A2u归属。
