ArticleJournal of the American Chemical Society2009
Structure of the biliverdin radical intermediate in phycocyanobilin:ferredoxin oxidoreductase identified by high-field EPR and DFT.
Article in Journal of the American Chemical Society, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers.
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10 citing papers in PubMed, 42 citations in OpenAlex.
- Evolutionary insights into bilin biosynthesis: Functional characterization of pre-PcyA enzymes.Protein science : a publication of the Protein Society · 2026Article
- Engineering of Phycourobilin Synthase: PubS to a Two-Electron Reductase.Plant & cell physiology · 2025Article
- Engineering stable radicals using photochromic triggers.Nature communications · 2020Article
- Biophysical Characterization of Fluorotyrosine Probes Site-Specifically Incorporated into Enzymes: E. coli Ribonucleotide Reductase As an Example.Journal of the American Chemical Society · 2016Article
- Dark-operative protochlorophyllide oxidoreductase generates substrate radicals by an iron-sulphur cluster in bacteriochlorophyll biosynthesis.Scientific reports · 2014Article
- Use of electron paramagnetic resonance to solve biochemical problems.Biochemistry · 2013Review
- Atomic hydrogen as high-precision field standard for high-field EPR.Journal of magnetic resonance (San Diego, Calif. : 1997) · 2010Article
- Biliverdin amides reveal roles for propionate side chains in bilin reductase recognition and in holophytochrome assembly and photoconversion.Biochemistry · 2010Article
- Structural basis for hydration dynamics in radical stabilization of bilin reductase mutants.Biochemistry · 2010Article
- Structural insights into vinyl reduction regiospecificity of phycocyanobilin:ferredoxin oxidoreductase (PcyA).The Journal of biological chemistry · 2010Article
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9 authors at 3 institutions in 1 country.
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Abstract
The cyanobacterial enzyme phycocyanobilin:ferredoxin oxidoreductase (PcyA) catalyzes the two-step four-electron reduction of biliverdin IXalpha to phycocyanobilin, the precursor of biliprotein chromophores found in phycobilisomes. It is known that catalysis proceeds via paramagnetic radical intermediates, but the structure of these intermediates and the transfer pathways for the four protons involved are not known. In this study, high-field electron paramagnetic resonance (EPR) spectroscopy of frozen solutions and single crystals of the one-electron reduced protein-substrate complex of two PcyA mutants D105N from the cyanobacteria Synechocystis sp. PCC6803 and Nostoc sp. PCC7120 are examined. Detailed analysis of Synechocystis D105N mutant spectra at 130 and 406 GHz reveals a biliverdin radical with a very narrow g tensor with principal values 2.00359(5), 2.00341(5), and 2.00218(5). Using density-functional theory (DFT) computations to explore the possible protonation states of the biliverdin radical, it is shown that this g tensor is consistent with a biliverdin radical where the carbonyl oxygen atoms on both the A and the D pyrrole rings are protonated. This experimentally confirms the reaction mechanism recently proposed (Tu, et al. Biochemistry 2007, 46, 1484).
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