羟基多氯联苯与人和大鼠羟基固醇类硫酸基转移酶的相互作用  

Interactions of hydroxylated polychlorinated biphenyls with human and rat hydroxysteroid sulfotransferases

作　　者：刘云岗[1] 屠鸿薇[1] 

机构地区：[1]南方医科大学公共卫生与热带医学学院毒理学系,广州510515

出　　处：《重庆医科大学学报》2011年第7期800-804,共5页Journal of Chongqing Medical University

基　　金：广东省高等学校人才引进专项基金资助项目(编号:粤财教[2010]343号)

摘　　要：目的:多氯联苯(Polychlorinated biphenyls,PCBs)是一类持久性环境污染物,对人类健康有潜在危害。羟基多氯联苯(Hydroxylated PCBs,OH-PCBs)是PCBs在体内的生物活性形式;已有报道OH-PCBs是多种亚型的酚类硫酸基转移酶(Sulfo-transferases,SULTs)抑制剂和底物,本研究拟观察OH-PCBs与人和大鼠羟基固醇类SULT有无相互作用。方法:采用重组表达人羟基固醇类SULT(SULT2A1)和其大鼠同源酶SULT2A3的大肠杆菌菌株,分离纯化所表达的酶蛋白;分析3种OH-PCBs的酶促硫酸基结合或抑制生理性底物结合反应的活性;以辅酶转化产物3’,5’-二磷酸腺苷(Adenosine 3’,5’-diphosphate,PAP)形成反映酶促硫酸基结合的水平。结果:4-OH PCB 34和4’-OH PCB 68一定浓度(1～200μmol/L)对人SULT2A1具有底物活性;二者都存在底物抑制(在50μmol/L以上抑制明显)。4’-OH PCB 9对此酶不具底物活性,但对去氢表雄酮(Dehydroepiandros-terone,DHEA)和1-甲醇基芘的酶促硫酸基结合有抑制作用,且呈竞争性抑制。不同的是3种OH-PCBs对大鼠SULT2A3都不具底物活性,且对该酶作用下以DHEA为底物的反应仅微弱抑制。结论:人和大鼠两个种属的羟基固醇类SULT对OH-PCBs的底物特异性及亲和力存在显著差异,OH-PCBs与人SULT2A1具有比与大鼠SULT2A3活跃的相互作用。Objective：Polychlorinated biphenyls（PCBs） are a group of persistent pollutants,which are potentially harmful to human health.Hydroxylated PCBs（OH-PCBs） are the biologically active form of PCBs,and there have been reports that OH-PCBs are potent inhibitors of phenol sulfotransferases（SULTs）;the present study was to investigate the interactions between OH-PCBs and hydroxysteroid SULTs of human and rat.Methods：Recombinant E.coli strains expressing human hydroxysteroid SULT（SULT2A1） and its rat homologous enzyme SULT2A3 were used as the sources of the expressed enzymes which were then purified to apparently homogeneous proteins;three OH-PCBs were applied to investigate their activities as substrates for the enzymes or inhibitors for the sulfation of other substrates;the enzyme activity was assayed by the formation of 3＇,5＇-diphosphoadenosine,the reaction product of the co-factor of SULTs.Results：4-OH PCB 34 and 4＇-OH PCB 68 were substrates for human SULT2A1;4＇-OH PCB 9 did not show substrate activity toward human SULT2A1;however,it inhibited the sulfation of dehydroepiandrosterone（DHEA）and 1-pyrenemethanol catalyzed by this enzyme,and in the mode of competitive inhibition.None of the three OH-PCBs were substrates for rat SULT2A3,nor did they show potent inhibition of the enzyme-catalyzed sulfation of DHEA,a physiologic substrate for the enzyme.Conclusion：There exist significant species differences between human and rat hydroxysteroid SULTs in their specificity and affinity toward OH-PCBs,with human SULT2A1 possessing much more active interactions with OH-PCBs than rat SULT2A3.

关 键 词：重组大肠杆菌 硫酸基转移酶 多氯联苯 羟基多氯联苯 

分 类 号：R963[医药卫生—微生物与生化药学]