Spectroscopic, electrochemical, and kinetic trends in Fe(III)–thiolate disproportionation near physiologic pH

IF 2.7 3区化学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY

JBIC Journal of Biological Inorganic Chemistry Pub Date : 2024-05-09 DOI:10.1007/s00775-024-02051-3

Levi A. Ekanger, Ruhi K. Shah, Matthew E. Porowski, Zach Ziolkowski, Alana Calello

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Abstract

In addition to its primary oxygen-atom-transfer function, cysteamine dioxygenase (ADO) exhibits a relatively understudied anaerobic disproportionation reaction (ADO-Fe(III)-SR → ADO-Fe(II) + ½ RSSR) with its native substrates. Inspired by ADO disproportionation reactivity, we employ [Fe(tacn)Cl₃] (tacn = 1,4,7-triazacyclononane) as a precursor for generating Fe(III)–thiolate model complexes in buffered aqueous media. A series of Fe(III)–thiolate model complexes are generated in situ using aqueous [Fe(tacn)Cl₃] and thiol-containing ligands cysteamine, penicillamine, mercaptopropionate, cysteine, cysteine methyl ester, N-acetylcysteine, and N-acetylcysteine methyl ester. We observe trends in UV–Vis and electron paramagnetic resonance (EPR) spectra, disproportionation rate constants, and cathodic peak potentials as a function of thiol ligand. These trends will be useful in rationalizing substrate-dependent Fe(III)–thiolate disproportionation reactions in metalloenzymes.

Graphical abstract

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生理 pH 值附近铁（III）-硫代酸歧化反应的光谱、电化学和动力学趋势。

除了其主要的氧原子转移功能外，半胱胺二氧合酶（ADO）还表现出与其原生底物的厌氧歧化反应（ADO-Fe(III)-SR → ADO-Fe(II) + ½ RSSR），而这种反应的研究相对较少。受 ADO歧化反应性的启发，我们采用[Fe(tacn)Cl3]（tacn = 1,4,7-三氮杂环壬烷）作为前体，在缓冲水介质中生成 Fe(III)-thiolate 模型复合物。我们使用水性[Fe(tacn)Cl3]和含硫醇配体半胱胺、青霉胺、巯基丙酸酯、半胱氨酸、半胱氨酸甲酯、N-乙酰半胱氨酸和 N-乙酰半胱氨酸甲酯原位生成了一系列硫代铁元素模型配合物。我们观察到紫外可见光谱和电子顺磁共振（EPR）光谱、歧化速率常数和阴极峰电位随硫醇配体变化的趋势。这些趋势将有助于合理解释金属酶中依赖于底物的铁(III)-硫醇酯歧化反应。

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来源期刊

JBIC Journal of Biological Inorganic Chemistry 化学-生化与分子生物学

CiteScore

5.90

自引率

3.30%

发文量

审稿时长

3 months

期刊介绍： Biological inorganic chemistry is a growing field of science that embraces the principles of biology and inorganic chemistry and impacts other fields ranging from medicine to the environment. JBIC (Journal of Biological Inorganic Chemistry) seeks to promote this field internationally. The Journal is primarily concerned with advances in understanding the role of metal ions within a biological matrix—be it a protein, DNA/RNA, or a cell, as well as appropriate model studies. Manuscripts describing high-quality original research on the above topics in English are invited for submission to this Journal. The Journal publishes original articles, minireviews, and commentaries on debated issues.