Component

N-Formyl-L-kynurenine

Initial product of tryptophan 2,3-dioxygenation; distinct from kynurenine.

5 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What acts on it

  1. Human IDO1 F226A, F227A and R231A mutants retained substrate binding but lacked catalytic activity.

    Human indoleamine 2,3-dioxygenase 1 / IDO1 → N-Formyl-L-kynurenine source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_access
    Primary abstract
    experimental_model
    Human enzyme site-directed mutagenesis.
    limitations
    Engineered mutants, not a characterized common dietary disorder.
    nutrient_topic
    Tryptophan collection; molecular form, preparation, species, exposure and manipulation remain explicit. · L-Tryptophan
    plain_language
    Binding the nutrient is not enough to process it.
    primary_references
    Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase. · 2006 · https://pubmed.ncbi.nlm.nih.gov/16477023/ · DOI 10.1073/pnas.0508996103
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Tryptophan: transport, protein synthesis, neuroactive metabolites, NAD and microbial pathways (2026-09-19) · lines 178–184

    AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human enzyme site-directed mutagenesis. · source_derived_draft · unverified_draft

    ## tryptophan-ido-binding-not-catalysis Binding the nutrient is not enough to process it. Human IDO1 F226A, F227A and R231A mutants retained substrate binding but lacked catalytic activity. Model: Human enzyme site-directed mutagenesis. Limitations: Engineered mutants, not a characterized common dietary disorder. Evidence access: Primary abstract Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase. · 2006 · https://pubmed.ncbi.nlm.nih.gov/16477023/ · DOI 10.1073/pnas.0508996103
    Complete structured claim and evidence

  2. Human IDO1 uses heme-bound oxygen to cleave the tryptophan indole ring, incorporating both oxygen atoms during N-formylkynurenine formation.

    Human indoleamine 2,3-dioxygenase 1 / IDO1 → N-Formyl-L-kynurenine source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Human IDO1 structure and mutagenesis.
    limitations
    Catalytic heme dependence does not establish benefit from extra dietary iron.
    nutrient_topic
    Tryptophan collection; molecular form, preparation, species, exposure and manipulation remain explicit. · L-Tryptophan
    plain_language
    An immune-regulated enzyme opens a different route for tryptophan.
    primary_references
    Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase. · 2006 · https://pubmed.ncbi.nlm.nih.gov/16477023/ · DOI 10.1073/pnas.0508996103

    Tryptophan: transport, protein synthesis, neuroactive metabolites, NAD and microbial pathways (2026-09-19) · lines 170–176

    AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Human IDO1 structure and mutagenesis. · source_derived_draft · unverified_draft

    ## tryptophan-ido-ring-cleavage An immune-regulated enzyme opens a different route for tryptophan. Human IDO1 uses heme-bound oxygen to cleave the tryptophan indole ring, incorporating both oxygen atoms during N-formylkynurenine formation. Model: Human IDO1 structure and mutagenesis. Limitations: Catalytic heme dependence does not establish benefit from extra dietary iron. Evidence access: Primary abstract Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase. · 2006 · https://pubmed.ncbi.nlm.nih.gov/16477023/ · DOI 10.1073/pnas.0508996103
    Complete structured claim and evidence

  3. Human TDO2 substrate and product structures support oxidative conversion of L-tryptophan and oxygen to N-formylkynurenine.

    Human tryptophan 2,3-dioxygenase / TDO2 → N-Formyl-L-kynurenine source_derived_draftungraded
    Experimental context and source evidence
    cross_nutrient
    Tryptophan provides the carbon framework entering the de novo niacin pathway; downstream steps remain necessary.
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/tdo2016.paragraphs.txt", "locator": "Normalized full-text paragraphs 9–9 (0-based)", "start_char": 8003, "end_char": 9136, "file_sha256": "3f91886745b8ff9fb808232c839dd346b03605dd025d5fa682a3de4f81338ec5", "text_sha256": "b39e2ce5d405e5eb8fde25aec369c306954365d7ec2b448fe5a5689e89785e2a"}
    experimental_model
    Purified human TDO2 crystallography and spectroscopy; substrate/product complexes
    exposure
    Biochemical or structural assay; no dietary intervention
    limitations
    Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    TDO2 opens the tryptophan ring at the beginning of the kynurenine route.
    primary_references
    [b3-pre-tdo2016] Molecular basis for catalysis and substrate-mediated cellular stabilization of human tryptophan 2,3-dioxygenase. (2016). https://pubmed.ncbi.nlm.nih.gov/27762317/ DOI: 10.1038/srep35169
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 479–491

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human TDO2 crystallography and spectroscopy; substrate/product complexes · source_derived_draft · unverified_draft

    ### b3-pre-tdo-reaction Human TDO2 substrate and product structures support oxidative conversion of L-tryptophan and oxygen to N-formylkynurenine. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: TDO2 opens the tryptophan ring at the beginning of the kynurenine route. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human TDO2 crystallography and spectroscopy; substrate/product complexes limitations: Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes. exposure: Biochemical or structural assay; no dietary intervention cross_nutrient: Tryptophan provides the carbon framework entering the de novo niacin pathway; downstream steps remain necessary. evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/tdo2016.paragraphs.txt", "locator": "Normalized full-text paragraphs 9–9 (0-based)", "start_char": 8003, "end_char": 9136, "file_sha256": "3f91886745b8ff9fb808232c839dd346b03605dd025d5fa682a3de4f81338ec5", "text_sha256": "b39e2ce5d405e5eb8fde25aec369c306954365d7ec2b448fe5a5689e89785e2a"} [b3-pre-tdo2016] Molecular basis for catalysis and substrate-mediated cellular stabilization of human tryptophan 2,3-dioxygenase. (2016). https://pubmed.ncbi.nlm.nih.gov/27762317/ DOI: 10.1038/srep35169
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Recombinant mouse Afmid hydrolyzed N-formyl-L-kynurenine with a Km of 0.18–0.19 mM, matching native mouse cytosolic enzyme.

    Mouse arylformamidase / Afmid → L-Kynurenine source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Mouse liver enzyme expressed in E. coli.
    limitations
    This experiment is mouse enzyme evidence, not direct human AFMID validation.
    nutrient_topic
    Tryptophan collection; molecular form, preparation, species, exposure and manipulation remain explicit. · L-Tryptophan
    plain_language
    A second enzyme removes the formyl group to produce kynurenine.
    primary_references
    Cloning, expression, and catalytic triad of recombinant arylformamidase. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15935693/ · DOI 10.1016/j.pep.2005.04.013

    Tryptophan: transport, protein synthesis, neuroactive metabolites, NAD and microbial pathways (2026-09-19) · lines 186–192

    AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Mouse liver enzyme expressed in E. coli. · source_derived_draft · unverified_draft

    ## tryptophan-afmid-hydrolysis A second enzyme removes the formyl group to produce kynurenine. Recombinant mouse Afmid hydrolyzed N-formyl-L-kynurenine with a Km of 0.18–0.19 mM, matching native mouse cytosolic enzyme. Model: Mouse liver enzyme expressed in E. coli. Limitations: This experiment is mouse enzyme evidence, not direct human AFMID validation. Evidence access: Primary abstract Cloning, expression, and catalytic triad of recombinant arylformamidase. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15935693/ · DOI 10.1016/j.pep.2005.04.013
    Complete structured claim and evidence

  2. S162A, D247A or H279A substitutions in mouse Afmid each removed more than 99% of measured enzyme activity.

    Mouse arylformamidase / Afmid → L-Kynurenine source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    machinery_impairment Imported condition classification; unverified.
    evidence_access
    Primary abstract
    experimental_model
    Recombinant mouse enzyme mutations.
    limitations
    Does not quantify human variant effects or prove a clinical repletion failure.
    nutrient_topic
    Tryptophan collection; molecular form, preparation, species, exposure and manipulation remain explicit. · L-Tryptophan
    plain_language
    One defective catalytic residue can block the next step despite available substrate.
    primary_references
    Cloning, expression, and catalytic triad of recombinant arylformamidase. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15935693/ · DOI 10.1016/j.pep.2005.04.013
    trigger_kind
    machinery_impairment Imported condition classification; unverified.

    Tryptophan: transport, protein synthesis, neuroactive metabolites, NAD and microbial pathways (2026-09-19) · lines 194–200

    AI-assisted research curation; primary-abstract references and experimental limitations individually identified. Not publisher full text. · supports · Recombinant mouse enzyme mutations. · source_derived_draft · unverified_draft

    ## tryptophan-afmid-triad One defective catalytic residue can block the next step despite available substrate. S162A, D247A or H279A substitutions in mouse Afmid each removed more than 99% of measured enzyme activity. Model: Recombinant mouse enzyme mutations. Limitations: Does not quantify human variant effects or prove a clinical repletion failure. Evidence access: Primary abstract Cloning, expression, and catalytic triad of recombinant arylformamidase. · 2005 · https://pubmed.ncbi.nlm.nih.gov/15935693/ · DOI 10.1016/j.pep.2005.04.013
    Complete structured claim and evidence

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

    This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

    Evidence, AI assistance and curation standards