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Stable nitroxyl radicals as pH, thiol and electron transfer probes

机译：稳定的硝酰基自由基，可作为pH，硫醇和电子转移探针

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摘要

In this review article original applications of stable nitroxyl radicals (SNRs) developed by the author with his students and colleagues are presented. ESR (electron spin resonance) spectra of SNRs of the imidazoline and imidazolidine types display high pH sensitivity. Mechanisms of proton exchange in such SNRs were studied in detail and made possible their wide application as pH probes (range of pH 0-13.5) in a variety of chemical and biological systems, including in vivo assays. A stable biradical, bis (2,2,5,5-tetramethyl-3-imidazoline-1-oxyl-4-il)-disulfide, was synthesized and used to monitor thiol-disulfide exchange with free thiols in solution. This approach permitted us to develop an extremely sensitive, quantitative and noninvasive method for determining the concentrations of glutathione and cysteine in living cells. The biradical was used to clarify the topography of cysteines in enzymes and to study their involvement in folding and stability of some proteins. We proposed and implemented a novel ESR approach to study electron transfer: the kinetics of photooxidation of an SNR (with concomitant production of an ESR-silent oxoammonium ion) by a Ru(III)-bipyridyl complex. Recovery of the ESR signal was observed when illumination was terminated. The rate of recovery depends strongly on the presence of organic electron donors, including some amino acids, and on pH. We used site-directed spin-labeled mutants of bacteriorhodopsin, to which a Ru(III) complex was also bound at a well-defined locus, to show the applicability of the proposed method to study the electron transfer and effects of local neighboring and water penetration in proteins. *** DIRECT SUPPORT *** A04RK041 00002
机译：在这篇评论文章中，介绍了作者与他的学生和同事一起开发的稳定硝氧基自由基（SNRs）的原始应用。咪唑啉和咪唑烷类型的SNR的ESR（电子自旋共振）光谱显示出较高的pH敏感性。对此类信噪比中质子交换的机理进行了详细研究，并使其在许多化学和生物学系统（包括体内测定法）中作为pH探针（pH 0-13.5范围）得到了广泛应用。合成了稳定的双自由基双（2,2,5,5-四甲基-3-咪唑啉-1-氧基-1-基）-二硫化物，并用于监测溶液中游离巯基与巯基-二硫化物的交换。这种方法使我们能够开发出一种极其灵敏，定量且无创的方法来测定活细胞中谷胱甘肽和半胱氨酸的浓度。使用双基来阐明酶中半胱氨酸的形貌，并研究它们在某些蛋白质的折叠和稳定性中的作用。我们提出并实施了一种新颖的ESR方法来研究电子转移：Ru（III）-联吡啶配合物对SNR（伴随产生ESR-沉默的氧铵离子）的光氧化动力学。当照明终止时，观察到ESR信号的恢复。回收率在很大程度上取决于有机电子给体（包括某些氨基酸）的存在以及pH值。我们使用定点自旋标记的细菌视紫红质的突变体，Ru（III）络合物也结合在一个明确定义的位置，以显示该方法的适用性，以研究电子转移以及对局部邻域和水的影响蛋白质渗透。 ***直接支持*** A04RK041 00002

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  • 来源
    《Applied Magnetic Resonance》 |2007年第4期|357-373|共17页
  • 作者

    L. M. Weiner;

  • 作者单位

    Department of Chemical Research Support Weizmann Institute of Science 76 100 Rehovot Israel;

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