Rao U M
Department of Medicine, The Nizam's Institute of Medical Sciences, Hyderabad, India.
Biochem Biophys Res Commun. 1989 Mar 31;159(3):1330-6. doi: 10.1016/0006-291x(89)92256-0.
Aqueous micelles of Triton X-100 were shown to catalyse the redox reaction between NADH and 2-p-iodophenyl-3-p-nitrophenyl-5-phenyltetrazolium chloride (INT) at the neutral pH. The transfer of reducing equivalents between the reactants in the micellar system appeared to be direct and quantitative. N-tert-butylphenyl-alpha-nitrone, a lipophilic free-radical scavenger which can enter micelles, and superoxide dismutase did not alter the stoichiometry of the reaction. The oxidation product of NADH was found to be 100% enzymatically active. The IR spectrum of INT-formazan (i.e., the product of INT reduction) showed an absorbance at 3,100-3,700 cm- due to NH-stretching. The presence of NH proton, confirmed further by IH-NMR, together with the above observations suggests that INT, as part of the over-all redox process, abstracts a C(4) hydrogen of the dihydropyridine nucleus of NADH with a simultaneous cleavage at N(2-3) position of its 1,2,3,4-tetrazole ring system and that the redox events are confined to a microenvironment as in the case of NAD(P)H-dependent enzymatic reactions.
已证明Triton X - 100的水相胶束在中性pH条件下能催化NADH与2 - 对碘苯基 - 3 - 对硝基苯基 - 5 - 苯基氯化四氮唑（INT）之间的氧化还原反应。胶束体系中反应物之间还原当量的转移似乎是直接且定量的。N - 叔丁基苯基 - α - 硝基酮是一种亲脂性自由基清除剂，可进入胶束，超氧化物歧化酶不会改变反应的化学计量。发现NADH的氧化产物具有100%的酶活性。INT - 甲臜（即INT还原产物）的红外光谱在3100 - 3700 cm⁻处显示出由于NH伸缩引起的吸光度。¹H - NMR进一步证实了NH质子的存在，结合上述观察结果表明，作为整体氧化还原过程的一部分，INT夺取NADH二氢吡啶核的C(4)氢，同时在其1,2,3,4 - 四唑环系统的N(2 - 3)位置发生裂解，并且氧化还原事件局限于一个微环境中，就像在依赖NAD(P)H的酶促反应中一样。
