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Sodium Dithionite

连二亚硫酸钠

Company: Sigma-Aldrich
Catalog#: 71699
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Determination of Flavin Potential in Proteins by Xanthine/Xanthine Oxidase Method
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Date:
2020-04-05
[Abstract]  This protocol describes a simple xanthine/xanthine oxidase enzymatic equilibration method for determination of the redox potential of a flavin. As an example of the use of this method, we determine the reduction potential of the covalently bound FAD cofactor (Em = -55 mV) in the SdhA flavoprotein subunit of succinate dehydrogenase from Escherichia coli. In principle, this method can be used routinely to determine the redox potential of flavin cofactors in any simple flavoprotein from equilibrium concentrations with an appropriate reference dye of known Em without the use of sophisticated electrochemical equipment. [摘要]  [摘要] 该协议描述了一种简单的黄嘌呤/黄嘌呤氧化酶酶平衡方法,用于测定黄素的氧化还原电位。作为使用此方法的一个例子,我们确定了大肠杆菌中琥珀酸脱氢酶的SdhA 黄素亚基中共价结合的FAD辅因子的还原电位(E m = -55 mV)。原则上,该方法可常规用于通过平衡浓度和已知E m 的适当参考染料确定任何简单黄素蛋白中黄素辅因子的氧化还原电位。 无需使用复杂的电化学设备。


[背景] 几种生物物理方法可用于测量蛋白质中黄素的还原中点电位(E m )。这些电位测量方法通常依赖于目标蛋白质和电极之间的电化学偶联。例如,在带有其他辅助因子(例如铁硫中心和醌)的复杂黄素蛋白中,常常使用电化学方法和电子顺磁共振(EPR)光谱来确定氧化还原中心的E m (Kowal 等,1995;Saenger等,等人,2005; Hudson 等人,2005; Cheng 等人,2015)。然而,在只包含黄素氧化还原中心简单黄素蛋白,辅助因子,可以直接通过它不需要特殊的设备电化学或昂贵的EPR仪表传统光学分光光度法研究。1990年,文森特·梅西(Vincent Massey)提出了一种简单的方法,该方法可以从氧化和还原伴侣(即黄素蛋白和参考染料)的平衡浓度中确定黄素的还原电位(Massey,1991)。该方法不直接测量黄素的还原电势,而是确定黄素和参考染料的E m ...

Measurement of Mitochondrial Respiration Rate in Maize (Zea mays) Leaves
Author:
Date:
2015-05-20
[Abstract]  Mitochondria play essential roles in plant growth and development as they host the oxidative phosphorylation pathways, tricarboxylic acid cycle and other important metabolisms. Disruption of mitochondrial functions frequently leads to embryo lethality. Moreover, mitochondria play roles in programmed cell death, pathogen and stress responses in plants. In contrast to animal mitochondria, plant mitochondria possess an additional electron transport pathway, the cyanide-resistant alternative pathway catalyzed by a single alternative oxidase (AOX). Unlike cytochrome pathway that is coupled to oxidative phosphorylation via proton translocation, electron transport from ubiquinol to AOX is non-phosphorylating. It releases the energy as heat. Chlorolab II liquid-phase oxygen electrode (Hansatech) ... [摘要]  线粒体在植物生长和发育中起重要作用,因为它们宿主氧化磷酸化途径,三羧酸循环和其他重要代谢。线粒体功能的破坏经常导致胚胎致死。此外,线粒体在程序性细胞死亡,病原体和植物应激反应中发挥作用。与动物线粒体相反,植物线粒体具有额外的电子传递途径,由单一备选氧化酶(AOX)催化的氰化物抗性替代途径。与通过质子易位与氧化磷酸化偶联的细胞色素途径不同,从泛素到AOX的电子转运是非磷酸化的。它释放能量作为热。 Chlorolab II液相氧电极(Hansatech)是一种高精度的Clark型氧电极,配有强大的WINDOWS软件,可以实时记录氧变化。其电极盘包括中心铂阴极和同心银阳极。电极盘连接到在铂和银电极之间施加小的极化电压的电极控制单元。在氧的存在下,产生与样品中的氧含量成比例的小电流。它可以敏感地和快速地对样品中氧含量的小变化作出响应。该协议描述如何测量线粒体总呼吸率,细胞色素通路能力以及具有chlorolab II氧电极的玉米叶中的替代途径能力。

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