Component

5-Phosphoribosyl 1-pyrophosphate

PRPP; activated phosphoribosyl donor.

4 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

Where it participates (unsigned role)

  1. Human NAMPT converts nicotinamide and PRPP to nicotinamide mononucleotide and pyrophosphate.

    Human nicotinamide phosphoribosyltransferase / NAMPT → NMN source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/nampt2009.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1272, "file_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5", "text_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5"}
    experimental_model
    Purified human NAMPT reaction monitoring by 1H/31P NMR and substrate/product crystallography
    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
    Nicotinamide salvage first makes NMN.
    primary_references
    [b3-pre-nampt2009] Structure and reaction mechanism of human nicotinamide phosphoribosyltransferase. (2010). https://pubmed.ncbi.nlm.nih.gov/19819904/ DOI: 10.1093/jb/mvp152
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 369–380

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human NAMPT reaction monitoring by 1H/31P NMR and substrate/product crystallography · source_derived_draft · unverified_draft

    ### b3-pre-nampt-reaction Human NAMPT converts nicotinamide and PRPP to nicotinamide mononucleotide and pyrophosphate. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Nicotinamide salvage first makes NMN. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human NAMPT reaction monitoring by 1H/31P NMR and substrate/product crystallography limitations: Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes. exposure: Biochemical or structural assay; no dietary intervention evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/nampt2009.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1272, "file_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5", "text_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5"} [b3-pre-nampt2009] Structure and reaction mechanism of human nicotinamide phosphoribosyltransferase. (2010). https://pubmed.ncbi.nlm.nih.gov/19819904/ DOI: 10.1093/jb/mvp152
    Complete structured claim and evidence

  2. NMR monitoring demonstrated reversibility of the purified human NAMPT reaction; the measured equilibrium constant was 0.14 under the study conditions.

    Human nicotinamide phosphoribosyltransferase / NAMPT → NMN source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/nampt2009.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1272, "file_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5", "text_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5"}
    experimental_model
    Purified human NAMPT reaction monitoring by 1H/31P NMR and substrate/product crystallography
    exposure
    Biochemical or structural assay; no dietary intervention
    limitations
    An isolated reaction equilibrium does not establish net intracellular salvage flux.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    This isolated chemical reaction can run in either direction.
    primary_references
    [b3-pre-nampt2009] Structure and reaction mechanism of human nicotinamide phosphoribosyltransferase. (2010). https://pubmed.ncbi.nlm.nih.gov/19819904/ DOI: 10.1093/jb/mvp152
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 382–393

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human NAMPT reaction monitoring by 1H/31P NMR and substrate/product crystallography · source_derived_draft · unverified_draft

    ### b3-pre-nampt-reversible NMR monitoring demonstrated reversibility of the purified human NAMPT reaction; the measured equilibrium constant was 0.14 under the study conditions. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: This isolated chemical reaction can run in either direction. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified human NAMPT reaction monitoring by 1H/31P NMR and substrate/product crystallography limitations: An isolated reaction equilibrium does not establish net intracellular salvage flux. exposure: Biochemical or structural assay; no dietary intervention evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/nampt2009.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1272, "file_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5", "text_sha256": "b67ca4decafccfc4132deba87ffddf2114e60542c77fa4354165d414aa0f13c5"} [b3-pre-nampt2009] Structure and reaction mechanism of human nicotinamide phosphoribosyltransferase. (2010). https://pubmed.ncbi.nlm.nih.gov/19819904/ DOI: 10.1093/jb/mvp152
    Complete structured claim and evidence

  3. Human NAPRT catalyzes phosphoribosyl transfer from PRPP to nicotinic acid, producing nicotinic acid mononucleotide and pyrophosphate.

    Human nicotinate phosphoribosyltransferase / NAPRT → Nicotinic acid mononucleotide source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/naprt2015.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1606, "file_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe", "text_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe"}
    experimental_model
    Recombinant human NAPRT crystallography and docking; purified protein, no intact tissue
    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
    Nicotinic acid enters its NAD-building route through NAPRT.
    primary_references
    [b3-pre-naprt2015] Crystal structure of human nicotinic acid phosphoribosyltransferase. (2015). https://pubmed.ncbi.nlm.nih.gov/26042198/ DOI: 10.1016/j.fob.2015.05.002
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 249–260

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human NAPRT crystallography and docking; purified protein, no intact tissue · source_derived_draft · unverified_draft

    ### b3-pre-naprt-reaction Human NAPRT catalyzes phosphoribosyl transfer from PRPP to nicotinic acid, producing nicotinic acid mononucleotide and pyrophosphate. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Nicotinic acid enters its NAD-building route through NAPRT. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Recombinant human NAPRT crystallography and docking; purified protein, no intact tissue limitations: Purified-enzyme evidence does not establish dietary intake requirements or clinical outcomes. exposure: Biochemical or structural assay; no dietary intervention evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/naprt2015.abstract.txt", "locator": "Indexed primary abstract", "start_char": 0, "end_char": 1606, "file_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe", "text_sha256": "df6e36cf3464d4cda171d06ee24065532dee0d8b5fd5c3ccafcb1cc8df951bbe"} [b3-pre-naprt2015] Crystal structure of human nicotinic acid phosphoribosyltransferase. (2015). https://pubmed.ncbi.nlm.nih.gov/26042198/ DOI: 10.1016/j.fob.2015.05.002
    Complete structured claim and evidence

  4. Human QPRT converts quinolinate and PRPP toward nicotinic acid mononucleotide; the human enzyme structures resolve reactant quinolinate and product NaMN complexes.

    Human quinolinate phosphoribosyltransferase / QPRT → Nicotinic acid mononucleotide source_derived_draftungraded
    Experimental context and source evidence
    evidence_span
    {"source_cache": "artifacts/niacin-precursors-sources/qprt2016.paragraphs.txt", "locator": "Normalized full-text paragraphs 13–15 (0-based)", "start_char": 10597, "end_char": 15612, "file_sha256": "85fcc4a79a17f4f3846301f67698a444c3c9930829e167d86a96adbb72d830e6", "text_sha256": "8da78d25a53af6507018eece4ce553705dc505d0b169f678affad49ee21b10f6"}
    experimental_model
    Purified recombinant human QPRT crystallography, calorimetry and oligomer studies
    exposure
    Biochemical or structural assay; no dietary intervention
    limitations
    Structural and biochemical enzyme study; does not establish how much dietary tryptophan becomes NAD in a person.
    nutrient_topic
    Niacin research collection; topical membership is not evidence of a direct dietary effect. · Niacin (vitamin B3)
    organism
    Homo sapiens
    plain_language
    Quinolinate enters the same deamidated mononucleotide route used by nicotinic acid.
    primary_references
    [b3-pre-qprt2016] Structural Insights into the Quaternary Catalytic Mechanism of Hexameric Human Quinolinate Phosphoribosyltransferase, a Key Enzyme in de novo NAD Biosynthesis. (2016). https://pubmed.ncbi.nlm.nih.gov/26805589/ DOI: 10.1038/srep19681
    supporting_evidence_spans
    [{"source_cache": "artifacts/niacin-precursors-sources/qprt2016.paragraphs.txt", "locator": "Normalized full-text paragraphs 4–4 (0-based)", "start_char": 1453, "end_char": 3871, "file_sha256": "85fcc4a79a17f4f3846301f67698a444c3c9930829e167d86a96adbb72d830e6", "text_sha256": "be14ed97ccf53b635f2cb35969188ce42c84dd739db897a24cbf3e65d8a3e3d1"}]
    tissue_or_cell_type
    Purified recombinant protein; no intact tissue

    Niacin: NAD metabolism, deficiency and nutrient interactions (2026-09-17) · lines 537–549

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human QPRT crystallography, calorimetry and oligomer studies · source_derived_draft · unverified_draft

    ### b3-pre-qprt-namn Human QPRT converts quinolinate and PRPP toward nicotinic acid mononucleotide; the human enzyme structures resolve reactant quinolinate and product NaMN complexes. Condition category: normal nutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect. plain_language: Quinolinate enters the same deamidated mononucleotide route used by nicotinic acid. organism: Homo sapiens tissue_or_cell_type: Purified recombinant protein; no intact tissue experimental_model: Purified recombinant human QPRT crystallography, calorimetry and oligomer studies limitations: Structural and biochemical enzyme study; does not establish how much dietary tryptophan becomes NAD in a person. exposure: Biochemical or structural assay; no dietary intervention evidence_span: {"source_cache": "artifacts/niacin-precursors-sources/qprt2016.paragraphs.txt", "locator": "Normalized full-text paragraphs 13–15 (0-based)", "start_char": 10597, "end_char": 15612, "file_sha256": "85fcc4a79a17f4f3846301f67698a444c3c9930829e167d86a96adbb72d830e6", "text_sha256": "8da78d25a53af6507018eece4ce553705dc505d0b169f678affad49ee21b10f6"} supporting_evidence_spans: [{"source_cache": "artifacts/niacin-precursors-sources/qprt2016.paragraphs.txt", "locator": "Normalized full-text paragraphs 4–4 (0-based)", "start_char": 1453, "end_char": 3871, "file_sha256": "85fcc4a79a17f4f3846301f67698a444c3c9930829e167d86a96adbb72d830e6", "text_sha256": "be14ed97ccf53b635f2cb35969188ce42c84dd739db897a24cbf3e65d8a3e3d1"}] [b3-pre-qprt2016] Structural Insights into the Quaternary Catalytic Mechanism of Hexameric Human Quinolinate Phosphoribosyltransferase, a Key Enzyme in de novo NAD Biosynthesis. (2016). https://pubmed.ncbi.nlm.nih.gov/26805589/ DOI: 10.1038/srep19681
    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