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

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作   者：

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

作者机构：

The College of New Jersey Department of Chemistry; 

关键词：

IRON(III);  Ligand binding;  COMPLEX;  MECHANISM;  Redox;  IRON CENTER;  CYSTEAMINE DIOXYGENASE;  ANAEROBIC OXIDATION;  CYSTEINE DIOXYGENASE;  Electrochemistry;  COMPUTATIONAL CHARACTERIZATION;  SUPEROXIDE REDUCTASE;  THIOL DIOXYGENASE;  Electron paramagnetic resonance;  Kinetics; 

期刊名称：

Journal of biological inorganic chemistry: JBIC: a publication of the Society of Biological Inorganic Chemistry

i s s n：

0949-8257

年卷期：

2024 年 29 卷 3 期

页   码：

291-301

页   码：

摘   要：

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) + 1/2 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.