Spectroscopic evidence supporting neutral thiol ligation to ferrous heme iron

Autor:	Nicole Frankenberg-Dinkel, Mark S. Hargrove, Masanori Sono, Anuja Modi, Shengfang Sun, John H. Dawson, Bastian Molitor
Rok vydání:	2018
Předmět:	inorganic chemicals 0301 basic medicine Hemeprotein Ethanethiol Heme Ligands 010402 general chemistry 01 natural sciences Biochemistry Ferrous Inorganic Chemistry 03 medical and health sciences chemistry.chemical_compound Thioether Coordination Complexes Polymer chemistry medicine Ferrous Compounds Sulfhydryl Compounds Molecular Structure Ligand 0104 chemical sciences 030104 developmental biology chemistry Ferric Spectrophotometry Ultraviolet Tetrahydrothiophene Cysteine medicine.drug
Zdroj:	JBIC Journal of Biological Inorganic Chemistry. 23:1085-1092
ISSN:	1432-1327 0949-8257
Popis:	The binding of neutral thiol (ethanethiol, EtSH) or thioether (tetrahydrothiophene, THT) to two types of heme proteins in their ferrous state has been investigated with UV-visible (UV-Vis) absorption and magnetic circular dichroism spectroscopy. For the second GAF (cGMP-specific phosphodiesterases, adenylyl cyclases, and FhlA) domain from the sensory kinase MsmS (sGAF2), stepwise additions of these respective two sulfur-donor ligands to its dithionite-reduced ferrous form generate homogeneous six-coordinate low-spin ferrous complexes at both pHs 7.0 and 5.4. Similar complexes were partially formed for deoxyferrous soybean leghemoglobin with EtSH or THT within their solubility limits in water. The titrations cause significant UV-Vis spectra changes attributable to a five-coordinate to six-coordinate heme iron coordination change. For sGAF2, the resulting spectra are essentially identical for the both ligands, clearly indicating the direct binding of neutral thiol/thioether to ferrous heme iron as the distal ligand. On the other hand, the thiol EtSH binds to ferric sGAF2 in the anionic thiolate form, while thioether THT forms its ferric sGAF2 complex as a neutral ligand. These observations provide compelling evidence that neutral cysteine is a plausible ligand for ferrous heme proteins.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::65a0f099c79a49f5a093c7f1c5af754d https://doi.org/10.1007/s00775-018-1611-3 Zobrazit plný text záznamu Plný text ve formátu PDF Plný text ve formátu HTML
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