Biomimetic studies on iodothyronine deiodinase intermediates: modeling the reduction of selenenyl iodide by thiols.
Enzyme mimetic studies on the crucial intermediate (E-SeI) of the iodothyronine deiodinase cycle have been carried out by using an areneselenenyl iodide stabilized by intramolecular Se.N interactions. Treatment of this compound with aromatic thiols and thiobenzoxazole in the presence of NEt(3) affords areneselenenyl sulfides that are stable towards disproportionation reactions. The structures of three of the areneselenenyl sulfides were determined by X-ray crystallography. In one case, in the absence of NEt(3), a diselenide can be formed rather than the selenenyl sulfide. The areneselenenyl iodide also reacts with a related selenol to produce the corresponding diselenide, and this reaction is found to be much faster than that with thiols. The high reactivity of the selenenyl iodide with the selenol suggests that a reduced selenol group (R'-SeH) may react with the E-SeI intermediate to produce a diselenide (E-Se-Se-R') without any thiol cosubstrate. The intermediacy of selenenyl sulfides during the reduction of selenenyl iodide by thiols and its possible relevance to the iodothyronine deiodinase catalytic cycle is also described.
Mugesh
Govindasamy
G
Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, 38023 Braunschweig, Germany.
du Mont
Wolf-Walther
WW
Wismach
Cathleen
C
Jones
Peter G
PG
D001665:Binding Sites; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007453:Iodide Peroxidase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012643:Selenium / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D018036:Selenium Compounds; D013438:Sulfhydryl Compounds; D007453:Iodide Peroxidase; D012643:Selenium