This review describes the use of cryoreduction/annealing EPR/ENDOR techniques for determining the active oxidizing species in reactions catalyzed by heme monooxygenases. The three candidate heme states are: ferric peroxo, ferric hydroperoxo and compound I intermediates. The enzymes discussed include cytochromes P450, nitric oxide synthase and heme oxygenase.
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http://dx.doi.org/10.1016/j.abb.2010.09.013 | DOI Listing |
J Am Chem Soc
January 2022
Department of Chemistry, Northwestern University, Evanston, Illinois 60201, United States.
In this report, we investigate the physical and chemical properties of monocopper Cu(I) superoxo and Cu(II) peroxo and hydroperoxo complexes. These are prepared by cryoreduction/annealing of the parent [LCu(O)] Cu(I) dioxygen adducts with the tripodal, N-coordinating, tetradentate ligands L = tmpa, tmpa, TMGtren and are best described as [LCu(O)] Cu(II) complexes that possess end-on (η-O) superoxo coordination. Cryogenic γ-irradiation (77 K) of the EPR-silent parent complexes generates mobile electrons from the solvent that reduce the [LCu(O)] within the frozen matrix, trapping the reduced form fixed in the structure of the parent complex.
View Article and Find Full Text PDFBiochemistry
December 2015
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States.
Cytochrome P450scc (CYP 11A1) catalyzes the conversion of cholesterol (Ch) to pregnenolone, the precursor to steroid hormones. This process proceeds via three sequential monooxygenation reactions: two hydroxylations of Ch first form 22(R)-hydroxycholesterol (HC) and then 20α,22(R)-dihydroxycholesterol (DHC); a lyase reaction then cleaves the C20-C22 bond to form pregnenolone. Recent cryoreduction/annealing studies that employed electron paramagnetic resonance (EPR)/electron nuclear double resonance (ENDOR) spectroscopy [Davydov, R.
View Article and Find Full Text PDFArch Biochem Biophys
March 2011
Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
This review describes the use of cryoreduction/annealing EPR/ENDOR techniques for determining the active oxidizing species in reactions catalyzed by heme monooxygenases. The three candidate heme states are: ferric peroxo, ferric hydroperoxo and compound I intermediates. The enzymes discussed include cytochromes P450, nitric oxide synthase and heme oxygenase.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!