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https://hdl.handle.net/2440/138167
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Type: | Journal article |
Title: | The binding of nitrogen-donor ligands to the ferric and ferrous forms of cytochrome P450 enzymes |
Author: | Mohamed, H. Ghith, A. Bell, S.G. |
Citation: | Journal of Inorganic Biochemistry, 2023; 242:112168-112168 |
Publisher: | Elsevier BV |
Issue Date: | 2023 |
ISSN: | 0162-0134 1873-3344 |
Statement of Responsibility: | Hebatalla Mohamed, Amna Ghith, Stephen G. Bell |
Abstract: | The cytochrome P450 superfamily of heme-thiolate monooxygenase enzymes can catalyse various oxidation reactions. The addition of a substrate or an inhibitor ligand induces changes in the absorption spectrum of these enzymes and UV-visible (UV-vis) absorbance spectroscopy is the most common and readily available technique used to interrogate their heme and active site environment. Nitrogen-containing ligands can inhibit the catalytic cycle of heme enzymes by interacting with the heme. Here we evaluate the binding of imidazole and pyridine-based ligands to the ferric and ferrous forms of a selection of bacterial cytochrome P450 enzymes using UV-visible absorbance spectroscopy. The majority of these ligands interact with the heme as one would expect for type II nitrogen directly coordinated to a ferric heme-thiolate species. However, the spectroscopic changes observed in the ligand-bound ferrous forms indicated differences in the heme environment across these P450 enzyme/ligand combinations. Multiple species were observed in the UV-vis spectra of the ferrous ligand-bound P450s. None of the enzymes gave rise to the isolation of a single species with a Soret band at ∼442-447 nm, indicative of a 6-coordinate ferrous thiolate species with a nitrogen-donor ligand. A ferrous species with Soret band at ∼427 nm coupled with an α-band of increased intensity was observed with the imidazole ligands. With some enzyme-ligand combinations reduction resulted in breaking of the iron‑nitrogen bond yielding a 5-coordinate high-spin ferrous species. In other instances, the ferrous form was readily oxidised back to the ferric form on addition of the ligand. |
Keywords: | Cytochrome P450; Heme-thiolate proteins; Ligand binding; UV–vis spectroscopy; Ferrous heme; Ferric heme |
Rights: | © 2023 Elsevier Inc. All rights reserved. |
DOI: | 10.1016/j.jinorgbio.2023.112168 |
Grant ID: | http://purl.org/au-research/grants/arc/FT140100355 |
Published version: | http://dx.doi.org/10.1016/j.jinorgbio.2023.112168 |
Appears in Collections: | Physics publications |
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