Prasanna H R, Lotlikar P D, Brandt C, Magee P N
Cancer Lett. 1985 Feb;26(1):25-32. doi: 10.1016/0304-3835(85)90169-7.
In vitro metabolism of dimethylnitrosamine (DMN) by liver microsomal fractions of hamster, rat and chicken revealed that the three species under certain assay conditions, were capable of metabolizing DMN at different rates (hamster greater than rat greater than chicken). The magnitude of the demethylase activity was found to be dependent on the nature of the buffer, the concentration of cytochrome P-450 (P-450) and the concentration of the substrate DMN. Enzyme activity was higher in Hepes buffer than in the phosphate buffer. Concentrations of phosphate higher than 20 mM inhibited the activity of the rat and chicken enzymes. This effect of phosphate was not a consequence of increase in ionic strength since KCl over a wide range of concentration failed to inhibit the activity.
仓鼠、大鼠和鸡的肝微粒体组分对二甲基亚硝胺（DMN）的体外代谢研究表明，在特定检测条件下，这三种物种能够以不同速率代谢DMN（仓鼠＞大鼠＞鸡）。发现去甲基酶活性的大小取决于缓冲液的性质、细胞色素P-450（P-450）的浓度以及底物DMN的浓度。在Hepes缓冲液中的酶活性高于磷酸盐缓冲液。高于20 mM的磷酸盐浓度会抑制大鼠和鸡的酶活性。磷酸盐的这种作用并非离子强度增加的结果，因为在广泛浓度范围内的KCl未能抑制该活性。
