Dixit Kiran, Ali Asif
Department of Biochemistry, Faculty of Medicine, A.M.U., Aligarh- 202002, India.
Life Sci. 2005 Oct 7;77(21):2626-42. doi: 10.1016/j.lfs.2005.02.026.
Peroxynitrite (ONOO(-)) is a strong and potent oxidizing and nitrating agent, formed by rapid reaction of two highly reactive, nitric oxide and superoxide anion. The action of peroxynitrite generated by synergistic action of diethylamine NONOate (a nitric oxide donor) and 1,4-hydroquinone (a superoxide donor), on human placental DNA was monitored by ultraviolet and fluorescence spectroscopy, melting temperature studies, S1 nuclease digestibility and alkaline agarose electrophoresis. The peroxynitrite modified human DNA (ONOO(-)-DNA) was found to be highly immunogenic in rabbits inducing high titre immunogen specific antibodies. However, the induced antibodies exhibited appreciable cross-reactivity with various polynucleotides and nucleic acids. The data demonstrate that the antibodies, though cross-reactive, preferentially bind ONOO(-)-modified epitopes on DNA. Visual detection of immune complex formation with native and ONOO(-)-DNA reiterated preferential binding with modified human DNA. DNA modified by ONOO(-) presents unique epitopes which may be one of the factors for the induction of autoantibodies in cancer patients.
过氧亚硝酸根（ONOO⁻）是一种强大且有效的氧化和硝化剂，由两种高反应性物质一氧化氮和超氧阴离子快速反应形成。通过紫外和荧光光谱、解链温度研究、S1核酸酶消化率以及碱性琼脂糖电泳，监测了二乙胺NONOate（一种一氧化氮供体）和1,4 - 对苯二酚（一种超氧阴离子供体）协同作用产生的过氧亚硝酸根对人胎盘DNA的作用。发现过氧亚硝酸根修饰的人DNA（ONOO⁻ - DNA）在兔体内具有高度免疫原性，可诱导产生高滴度的免疫原特异性抗体。然而，诱导产生的抗体与各种多核苷酸和核酸表现出明显的交叉反应性。数据表明，这些抗体虽然具有交叉反应性，但优先结合DNA上的ONOO⁻修饰表位。对天然DNA和ONOO⁻ - DNA免疫复合物形成的可视化检测再次证明了与修饰的人DNA的优先结合。ONOO⁻修饰的DNA呈现出独特的表位，这可能是癌症患者诱导自身抗体产生的因素之一。
