The present invention provides methods, compositions, substrates, and kits useful for analyzing the metabolic activity in cells, tissue, and animals and for screening test compounds for their effect on cytochrome P450 activity. In particular, a one-step and two-step methods using luminogenic molecules, e.g. luciferin or coelenterazines, that are cytochrome P450 substrates and that are also bioluminescent enzyme, e.g., luciferase, pro-substrates are provided. Upon addition of the luciferin derivative or other luminogenic molecule into a P450 reaction, the P450 enzyme metabolizes the molecule into a bioluminescent enzyme substrate, e.g., luciferin and/or luciferin derivative metabolite, in a P450 reaction. The resulting metabolite(s) serves as a substrate of the bioluminescent enzyme, e.g., luciferase, in a second light-generating reaction. Luminescent cytochrome P450 assays with low background signals and high sensitivity are disclosed and isoform selectivity is demonstrated. The present invention also provides an improved method for performing luciferase reactions which employs added pyrophosphatase to remove inorganic pyrophosphate, a luciferase inhibitor which may be present in the reaction mixture as a contaminant or may be generated during the reaction. The present method further provides a method for stabilizing and prolonging the luminescent signal in a luciferase-based assay using luciferase stabilizing agents such as reversible luciferase inhibitors.
本发明提供了用于分析细胞、组织和动物代谢活性以及筛选化合物对细胞色素P450活性影响的方法、组成物、底物和试剂盒。特别地,提供了使用发光分子(如
荧光素或发光虫菊素)的一步和两步方法,这些分子是细胞色素P450底物,也是
生物发光酶(如
荧光素酶)的前体底物。将
荧光素衍
生物或其他发光分子加入到P450反应中后,P450酶将这些分子代谢成
生物发光酶底物(如
荧光素和/或
荧光素衍
生物代谢物)的底物。产生的代谢物作为
生物发光酶(如
荧光素酶)的底物,在第二个发光反应中发光。揭示了低背景信号和高灵敏度的发光细胞色素P450测定方法,并证明了亚型选择性。本发明还提供了一种改进的
荧光素酶反应方法,该方法采用添加
焦磷酸酶以去除无机
焦磷酸盐,该酶是可能存在于反应混合物中的污染物或在反应过程中生成的
荧光素酶抑制剂。本方法进一步提供了一种使用可逆
荧光素酶抑制剂等
荧光素酶稳定剂稳定和延长
荧光素酶基础测定中的发光信号的方法。