Department of Civil and Environmental Engineering and IIHR Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa 52242, United States.
Environ Sci Technol. 2013 Jul 2;47(13):6829-35. doi: 10.1021/es304298m. Epub 2013 Jan 24.
Cytochromes P450 (CYPs) are potential enzymes responsible for hydroxylation of many xenobiotics and endogenous chemicals in living organisms. It has been found that 4-monochlorobiphenyl (PCB3), mainly an airborne pollutant, can be metabolized to hydroxylated transformation products (OH-PCB3s) in whole poplars. However, the enzymes involved in the hydroxylation of PCB3 in whole poplars have not been identified. Therefore, two CYP suicide inhibitors, 1-aminobenzotriazole (ABT) and 17-octadecynoic acid (ODYA), were selected to probe the hydroxylation reaction of PCB3 in whole poplars in this work. Poplars (Populus deltoides × nigra, DN34) were exposed to PCB3 with or without inhibitor for 11 days. Results showed both ABT and ODYA can decrease the concentrations and yields of five OH-PCB3s in different poplar parts via the inhibition of CYPs. Furthermore, both ABT and ODYA demonstrated a dose-dependent relationship to the formation of OH-PCB3s in whole poplars. The higher the inhibitor concentrations, the lower the total yields of OH-PCB3s. For ABT spiked-additions, the total mass yield of five OH-PCB3s was inhibited by a factor of 1.6 times at an ABT concentration of 2.5 mg L(-1), 4.0 times at 12.5 mg L(-1), and 7.0 times at 25 mg L(-1). For the inhibitor ODYA, the total mass of five OH-PCB3s was reduced by 2.1 times compared to the control at an ODYA concentration of 2.5 mg L(-1). All results pointed to the conclusion that CYP enzymes were the agents which metabolized PCB3 to OH-PCB3s in whole poplars because suicide CYP inhibitors ABT and ODYA both led to sharp decreases of OH-PCB3s formation in whole poplars. A dose-response curve for each of the suicide inhibitors was developed.
细胞色素 P450（CYPs）是负责许多外来生物和生物体内源性化学物质羟化的潜在酶。已经发现，4-单氯联苯（PCB3），主要是一种空气污染物，可以在整个杨树中代谢为羟化转化产物（OH-PCB3s）。然而，在整个杨树上参与 PCB3 羟化的酶尚未确定。因此，本研究选择了两种 CYP 自杀抑制剂 1-氨基苯并三唑（ABT）和 17-辛炔酸（ODYA）来探测整个杨树上 PCB3 的羟化反应。杨树（杂种黑杨×欧美杨，DN34）用或不用抑制剂暴露于 PCB3 中 11 天。结果表明，ABT 和 ODYA 均可通过抑制 CYP 降低不同杨树部位五种 OH-PCB3s 的浓度和产率。此外，ABT 和 ODYA 均表现出对整个杨树中 OH-PCB3s 形成的剂量依赖性关系。抑制剂浓度越高，OH-PCB3s 的总产量越低。对于 ABT 加标添加，在 ABT 浓度为 2.5 mg L(-1)时，五种 OH-PCB3s 的总质量产率抑制了 1.6 倍，在 12.5 mg L(-1)时抑制了 4.0 倍，在 25 mg L(-1)时抑制了 7.0 倍。对于抑制剂 ODYA，与对照相比，五种 OH-PCB3s 的总质量减少了 2.1 倍。所有结果都表明 CYP 酶是将 PCB3 代谢为 OH-PCB3s 的代谢物，因为自杀 CYP 抑制剂 ABT 和 ODYA 都会导致整个杨树上 OH-PCB3s 形成急剧减少。为每种自杀抑制剂开发了剂量-反应曲线。
