Evidence map›Paper›PMID 42670920›Full record

ArticleInorganic chemistry2026

Evidence for the Formation of an Iron(III)-Indolenylperoxo Intermediate During Indole Dioxygenation: Similarities with Heme Dioxygenases.

Boya Feng, Guy N L Jameson, David P Goldberg

Abstract read
In one paragraph

Article in Inorganic chemistry, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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4 · The record

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5 · Who and what money

Authors and funding

3 authors.

Boya FengDepartment of Chemistry, The Johns Hopkins University, Baltimore, Maryland21218, United States.
Guy N L JamesonSchool of Chemistry, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road, Parkville, Victoria3010, Australia.ORCID 0000-0001-9416-699X
David P GoldbergDepartment of Chemistry, The Johns Hopkins University, Baltimore, Maryland21218, United States.ORCID 0000-0003-4645-1045

Funding

Reactivity of Manganese and Iron Metalloenzyme ModelsR01GM101153 · NIGMS · JOHNS HOPKINS UNIVERSITY · PI GOLDBERG, DAVID P · 2013 to 2023
$3.4M
Heme and Nonheme Transition Metal Complexes, Reactivity, and MechanismR35GM149233 · NIGMS · JOHNS HOPKINS UNIVERSITY · PI David P Goldberg · 2023 to 2026
$2.1M
NIGMS NIH HHS R01 GM101153NIGMS NIH HHS R35 GM149233NIH HHS R01GM101153NIH HHS R35GM149233
6 · The paper itself

Abstract

Evidence for an iron(III)-indolenylperoxo (OOIn-) complex, [FeIII(OOIn)(TPP)(OCH3)]- (TPP = 5,10,15,20-tetraphenylporphyrinato2-) trapped at -78 °C, was obtained. The formation of this species was initiated by reaction of either FeIII(TPP)(Cl) in the presence of excess O2, OCH3- as axial ligand and base, and 3-methylindole, or from reaction of preformed [FeIII(O2•-)(TPP)(OCH3)]- with 3-methylindole under the same basic conditions. The new species was characterized by UV-vis, X-band EPR, and Mössbauer spectroscopies. Interestingly, the EPR spectra of [FeIII(OOIn)(TPP)(OCH3)]- exhibited two overlapping low-spin (S = 1/2) rhombic signals (A: g = [2.31, 2.20, 1.93]; B: g = [2.24, 2.15, 1.96]), whose ratios are sensitive to the amount of MeOH in the solvent mixture MeOH/toluene. The two sets of EPR signals (A and B) were assigned as arising from the presence or absence of hydrogen bonding between the OCH3- axial ligand and the solvent MeOH. This assignment was supported by analysis of ligand field splitting parameters derived from the EPR data. Addition of 1-methylimidazole (1-MeIm) to [FeIII(OOIn)(TPP)(OCH3)]- at -78 °C leads to conversion of the two overlapping rhombic EPR signals into a new, single S = 1/2 rhombic spectrum with g = [2.31, 2.18, 1.94] and a sharper Mössbauer spectrum. These data are consistent with substitution of OCH3- axial ligand by 1-MeIm to give FeIII(OOIn)(TPP)(1-MeIm). Thermal decay of the iron(III)-indolenylperoxo complex gives the ring-opened, dioxygenated product N-(2-acetylphenyl)formamide (75% by GC-MS). The capability of [FeIII(OOIn)(TPP)(OCH3)]- to convert into dioxygenated product indicates that iron indolenylperoxide is a possible intermediate of the indole dioxygenation process. This work has implications for the proposed mechanisms of tryptophan/indoleamine 2,3-dioxygenase (TDO/IDO) and demonstrates a feasible pathway for dioxygenation mediated by a single iron porphyrin complex.

Indexed as

DioxygenasesFerric CompoundsHemeIndolesOxygenModels, MolecularMolecular StructureDioxygenasesFerric CompoundsHemeIndolesOxygen

Identifiers

PMID42670920
PMCPMC13533448

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