Acidity of persulfides and its modulation by the protein environments in sulfide quinone oxidoreductase and thiosulfate sulfurtransferase
作者:Dayana Benchoam、Ernesto Cuevasanta、Joseph V. Roman、Ruma Banerjee、Beatriz Alvarez
DOI:10.1016/j.jbc.2024.107149
日期:2024.5
sulfide quinone oxidoreductase and thiosulfate sulfurtransferase (TST, rhodanese). The pH dependence of the activities of both enzymes was measured using sulfite and/or cyanide as sulfur acceptors. The TST half-reactions were also studied by stopped-flow fluorescence spectroscopy. Both persulfidated enzymes relied on protonated groups for reaction with the acceptors. Persulfidated sulfide quinone oxidoreductase
过硫化物 (RSSH/RSS) 参与硫代谢,并被提议转导硫化氢 (HS) 信号转导。人们对它们的生化特性知之甚少。在此,我们使用烷化剂单溴二甲苯研究了几种低分子量过硫化物的酸性和亲核性。不同的过硫化物表现出相似的 p 值 (4.6-6.3) 和与 pH 无关的速率常数 (3.2-9.0 × 10 M s),表明过硫化物中的取代基对性能的影响程度小于硫醇,因为与外层硫的距离较大。过硫化物与单溴二甲胯的反应性高于类似硫醇和具有相同 p 的推定硫醇,为 α 效应提供了证据(通过存在具有高电子密度的连续原子来增强亲核性)。此外,我们研究了来自人线粒体 HS 氧化途径的两种形成催化过硫化物中间体的酶,硫化物醌氧化还原酶和硫代硫酸盐硫转移酶 (TST,罗丹尼斯)。使用亚硫酸盐和/或氰化物作为硫受体来测量两种酶活性的 pH 依赖性。还通过停流荧光光谱研究了 TST 半反应。两种过硫化酶都依赖于质子化基团与受体反应。过硫化醌氧化还原酶的
Enzymatic and non-enzymatic conversion of cystamine to thiotaurine and taurine
作者:Steven J. Karpowicz、Lauren Anderson
DOI:10.1016/j.bbagen.2022.130225
日期:2022.12
disulfide-containing molecule cystamine and the thiosulfonate thiotaurine are of interest as therapeutics. Both are precursors of taurine, but the chemistry of their metabolism is not clear. The rates at which these molecules are metabolized is also unknown. The chemistry and rate constants have been determined for a process in which cystamine is converted in four reactions to thiotaurine. Cystamine is oxidized by