ArticleArchives of biochemistry and biophysics2015
Catalytic activity of human indoleamine 2,3-dioxygenase (hIDO1) at low oxygen.
Article in Archives of biochemistry and biophysics, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 11 papers.
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The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
11 citing papers in PubMed.
- Differential Effects of Saturated and Unsaturated Fatty Acids on Colorectal Cancer via IDO1 Signaling.Cancer medicine · 2026Article
- Electrochemical Analysis and Inhibition Assay of Immune-Modulating Enzyme, Indoleamine 2,3-Dioxygenase.Pharmaceuticals (Basel, Switzerland) · 2025Article
- Review
- Indoleamine 2,3-dioxygenase 1 (IDO1): an up-to-date overview of an eclectic immunoregulatory enzyme.The FEBS journal · 2022Review
- Carbon Monoxide Signaling: Examining Its Engagement with Various Molecular Targets in the Context of Binding Affinity, Concentration, and Biologic Response.Pharmacological reviews · 2022Review
- One Key and Multiple Locks: Substrate Binding in Structures of Tryptophan Dioxygenases and Hydroxylases.ChemMedChem · 2021Review
- Indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors in clinical trials for cancer immunotherapy.Journal of hematology & oncology · 2021Review
- Advances in indoleamine 2,3-dioxygenase 1 medicinal chemistry.MedChemComm · 2017Review
- A short history of heme dioxygenases: rise, fall and rise again.Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry · 2017Review
- Different Mechanisms of Catalytic Complex Formation in Two L-Tryptophan Processing Dioxygenases.Frontiers in molecular biosciences · 2017Review
- Prostate cancer immunotherapy, particularly in combination with androgen deprivation or radiation treatment. Customized pharmacogenomic approaches to overcome immunotherapy cancer resistance.Il Giornale di chirurgiaReview
Corrections and comments
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Authors and funding
5 authors.
Funding
Abstract
A cytokine-inducible extrahepatic human indoleamine 2,3-dioxygenase (hIDO1) catalyzes the first step of the kynurenine pathway. Immunosuppressive activity of hIDO1 in tumor cells weakens host T-cell immunity, contributing to the progression of cancer. Here we report on enzyme kinetics and catalytic mechanism of hIDO1, studied at varied levels of dioxygen (O2) and L-tryptophan (L-Trp). Using a cytochrome b5-based activating system, we measured the initial rates of O2 decay with a Clark-type oxygen electrode at physiologically-relevant levels of both substrates. Kinetics was also studied in the presence of two substrate analogs: 1-methyl-L-tryptophan and norharmane. Quantitative analysis supports a steady-state rather than a rapid equilibrium kinetic mechanism, where the rates of individual pathways, leading to a ternary complex, are significantly different, and the overall rate of catalysis depends on contributions of both routes. One path, where O2 binds to ferrous hIDO1 first, is faster than the second route, which starts with the binding of L-Trp. However, L-Trp complexation with free ferrous hIDO1 is more rapid than that of O2. As the level of L-Trp increases, the slower route becomes a significant contributor to the overall rate, resulting in observed substrate inhibition.
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Registered trials
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