Instituto de Química, UNAM, Circuito Exterior s/n, Ciudad Universitaria, México D.F. 04510, Mexico.
Instituto de Química, UNAM, Circuito Exterior s/n, Ciudad Universitaria, México D.F. 04510, Mexico.
J Inorg Biochem. 2014 May;134:20-4. doi: 10.1016/j.jinorgbio.2014.01.008. Epub 2014 Jan 22.
Three cyclometalated and one coordination compounds Os(C-N)x(bpy)3-x (x/m=0/2+ (4); 1/1+ (3); 2/1+ (2); 3/0 (1); (-)C-N=2-phenylpyridinato, bpy=2,2'-bipyridine) with drastically different reduction potentials have been used for analyzing the second-order rate constants for one-electron, metal-based osmium(II) to osmium(III) oxidation of the complexes by compound I (k2) and compound II (k3) of horseradish peroxidase. Previously unknown k2 and k3 have been determined by digital simulation of cyclic voltammograms measured in phosphate buffer of pH7.6 and 21 ± 1°C. Osmium(II) species derived from osmium(III) complexes 1 and 2 were generated electrochemically in situ. Under the conditions used the reduction potentials for the Os(III/II) feature equal -0.90, -0.095, 0.23 and 0.85V versus NHE (normal hydrogen electrode) for 1-4, respectively. The rate constants k2 equal ~5 × 10(7), 6 × 10(8), 2 × 10(6) and 1 × 10(5)M(-1)s(-1) and the rate constants k3 equal ~9 × 10(6), 4× 10(7), 1 ×10(6) and 1 × 10(5)M(-1)s(-1) for complexes 1-4, respectively. Both rate constants k2 and k3 first increase with increasing the reaction driving force on going from 4 to 2 but then both decrease on going to complex 1 though the reaction driving force is the highest in this case. The system described has been explored theoretically using docking Monte Carlo simulations.
三种偕二膦酸和一种配位化合物 Os(C-N)x(bpy)3-x (x/m=0/2+ (4); 1/1+ (3); 2/1+ (2); 3/0 (1); (-)C-N=2-苯基吡啶甲酸盐，bpy=2,2'-联吡啶)，具有截然不同的还原电位，用于分析辣根过氧化物酶的复合物 I (k2) 和复合物 II (k3) 进行的单电子、基于金属的锇(II)到锇(III)氧化的二级速率常数。通过在 pH7.6 和 21±1°C 的磷酸盐缓冲液中测量的循环伏安法的数字模拟，确定了以前未知的 k2 和 k3。锇(II)物种是从锇(III)配合物 1 和 2 电化学原位生成的。在使用的条件下，Os(III/II)特征的还原电位对于 1-4 分别为 -0.90、-0.095、0.23 和 0.85V 与 NHE（标准氢电极）相对。速率常数 k2 分别为 ~5×10(7)、6×10(8)、2×10(6) 和 1×10(5)M(-1)s(-1)，k3 分别为 ~9×10(6)、4×10(7)、1×10(6) 和 1×10(5)M(-1)s(-1)对于复合物 1-4。速率常数 k2 和 k3 均随着反应驱动力从 4 增加到 2 而增加，但随后在复合物 1 时均减小，尽管在这种情况下反应驱动力最高。使用对接 Monte Carlo 模拟对所描述的系统进行了理论探讨。
