McCue J P, Kennedy J H
Bioinorg Chem. 1977;7(1):5-21. doi: 10.1016/s0006-3061(00)80125-8.
The air oxidation of procarbazine in the presence of Ti(IV) was examined as a model system for the effects titanium has on oxidative processes and intermediates involving molecular oxygen. It was found that Ti(IV) inhibited oxidation when the substrate, procarbazine, was coordinated to titanium. This inhibition was most prominent (reduction of overall rate constant by a factor of 10(2)) in its interference with Cu(II) catalyzed oxidation of the substrate whole oxidation by the neutral species O2 was only slightly inhibited (factor of 2). However, when Mn(II) was used to catalyze the oxidation of procarbazine by air, titanium enhanced the catalytic effect of Mn(II) by a factor of 10(2). This enhancement was found to be due to Ti(IV) catalysis of the air oxidation of Mn(II), and the effect was found to be inhibited by catalase but not superoxide dismutase or peroxidase. These results are discussed in terms of a Ti(IV) ability to activate molecular oxygen and its ability to form oxygen free-radical complexes.
研究了在Ti(IV)存在下丙卡巴肼的空气氧化反应，以此作为钛对涉及分子氧的氧化过程及中间体影响的模型体系。研究发现，当底物丙卡巴肼与钛配位时，Ti(IV)会抑制氧化反应。这种抑制在其干扰Cu(II)催化的底物氧化反应中最为显著（总速率常数降低10²倍），而中性物种O₂对底物的整体氧化反应仅略有抑制（2倍）。然而，当使用Mn(II)催化丙卡巴肼的空气氧化反应时，钛使Mn(II)的催化效果增强了10²倍。发现这种增强是由于Ti(IV)催化了Mn(II)的空气氧化反应，并且该效果被过氧化氢酶抑制，但不被超氧化物歧化酶或过氧化物酶抑制。从Ti(IV)激活分子氧的能力及其形成氧自由基络合物的能力方面对这些结果进行了讨论。
