Vol'dman Iu Iu, Guliaeva L F, Vaĭner L M, Liakhovich V V
Bioorg Khim. 1989 Aug;15(8):1044-55.
Acceleration of substrate longitudinal relaxation (T1) was used to study cytochrome P-450-aminopyrine (1st type substrate) and P-450-4-methoxypyridine (2nd type substrate) complexes. Dissociation constant, T1 and/or residence time of substrate in the complex can be obtained from the dependence of T1 of substrate protons on substrate concentration. Basing on the relaxation times, distances between Fe3+ ion in the active site and protons of the substrate moiety were determined. For aminopyrine all the distances proved to be about 8 A. In the P-450-4-methoxypyridine complex the pyridine nitrogen is directed towards Fe3+ ion. Cytochrome P-450 is compared with its denatured form, cytochrome P-420, and metmyoglobin.
利用底物纵向弛豫（T1）加速来研究细胞色素P - 450 - 氨基吡啶（第一类底物）和P - 450 - 4 - 甲氧基吡啶（第二类底物）复合物。底物质子的T1对底物浓度的依赖性可得出复合物中底物的解离常数、T1和/或停留时间。基于弛豫时间，确定了活性位点中Fe3 +离子与底物部分质子之间的距离。对于氨基吡啶，所有距离均约为8埃。在P - 450 - 4 - 甲氧基吡啶复合物中，吡啶氮指向Fe3 +离子。将细胞色素P - 450与其变性形式细胞色素P - 420以及高铁肌红蛋白进行了比较。
