title: Probing bis-Fe(IV) MauG: experimental evidence for the long-range charge-resonance model.
abstract: The biosynthesis of tryptophan tryptophylquinone, a protein-derived cofactor, involves a long-range reaction mediated by a bis-Fe(IV) intermediate of a diheme enzyme, MauG. Recently, a unique charge-resonance (CR) phenomenon was discovered in this intermediate, and a biological, long-distance CR model was proposed. This model suggests that the chemical nature of the bis-Fe(IV) species is not as simple as it appears; rather, it is composed of a collection of resonance structures in a dynamic equilibrium. Here, we experimentally evaluated the proposed CR model by introducing small molecules to, and measuring the temperature dependence of, bis-Fe(IV) MauG. Spectroscopic evidence was presented to demonstrate that the selected compounds increase the decay rate of the bis-Fe(IV) species by disrupting the equilibrium of the resonance structures that constitutes the proposed CR model. The results support this new CR model and bring a fresh concept to the classical CR theory.
authors: Department of Chemistry and Center for Diagnostics & Therapeutics, Georgia State University, Atlanta, GA (USA) http://Feradical.gsu.edu.
authors: Jiafeng
authors: J
authors: Geng
authors: Ian
authors: I
authors: Davis
authors: Aimin
authors: A
authors: Liu
mesh_terms: D019943:Amino Acid Substitution; D004578:Electron Spin Resonance Spectroscopy; D006418:Heme / Q000737:chemistry*; D006420:Hemeproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D045563:Indolequinones / Q000096:biosynthesis / Q000737:chemistry; D008958:Models, Molecular; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry / Q000378:metabolism; D019265:Spectroscopy, Near-Infrared; D013696:Temperature; D014364:Tryptophan / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000737:chemistry
chemical_list: D006420:Hemeproteins; D045563:Indolequinones; C070569:tryptophan tryptophylquinone; D006418:Heme; D014364:Tryptophan; C021567:methylamine dehydrogenase; D000587:Oxidoreductases Acting on CH-NH Group Donors
keywords: charge resonance; electronic structure; heme proteins; high-valence iron; near-infrared spectroscopy
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