Component
PNPO Arg229Trp protein
Disease-associated R229W protein substitution affecting FMN and substrate interactions.
2 recorded relationships. Experimental role, claim status and evidence remain attached to each record.
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.
Other things that act on it
Enzymes, hormones, genes, and other components with a recorded effect. These are not nutrients, so they do not count toward the arrows above. Each finding names the chapter that recorded it.
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.
What it acts on
R229W PNPO showed approximately 850-fold lower PNP catalytic efficiency, combining a 192-fold higher Km and 4.5-fold lower kcat.
Experimental context and source evidence
- availability_state
- machinery_impairment Imported condition classification; unverified.
- cross_nutrient
- B2-cofactor binding is one part of a broader genetic defect in B6 activation.
- evidence_location
- Results: Table 3 and Fig 1; Table 2 and Fig 2
- experimental_model
- Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure.
- exposure
- Purified-enzyme assay
- limitations
- Km is a kinetic parameter, not a direct binding constant; adding FMN alone was not shown to normalize this whole defect.
- nutrient_topic
- Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
- organism
- Homo sapiens
- plain_language
- The defect also changes substrate handling and reaction speed.
- primary_references
- [musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372
- tissue_or_cell_type
- Purified recombinant enzyme; no intact tissue
- trigger_kind
- machinery_impairment Imported condition classification; unverified.
Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1220–1232
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. · source_derived_draft · unverified_draft
### b2-pnpo-r229w-catalytic-efficiency R229W PNPO showed approximately 850-fold lower PNP catalytic efficiency, combining a 192-fold higher Km and 4.5-fold lower kcat. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The defect also changes substrate handling and reaction speed. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. limitations: Km is a kinetic parameter, not a direct binding constant; adding FMN alone was not shown to normalize this whole defect. exposure: Purified-enzyme assay cross_nutrient: B2-cofactor binding is one part of a broader genetic defect in B6 activation. evidence_location: Results: Table 3 and Fig 1; Table 2 and Fig 2 [musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372
Complete structured claim and evidenceR229W PNPO had an FMN dissociation constant approximately 50-fold higher than wild type in apoenzyme fluorescence titrations.
Experimental context and source evidence
- availability_state
- machinery_impairment Imported condition classification; unverified.
- cross_nutrient
- A B6-activation disorder directly disrupts B2-cofactor binding.
- evidence_location
- Results: Table 3 and Fig 1; Table 2 and Fig 2
- experimental_model
- Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure.
- exposure
- Purified-enzyme assay
- limitations
- Biochemical evidence does not establish a dietary threshold or supplementation benefit.
- nutrient_topic
- Riboflavin research collection; topical membership is not evidence of a direct dietary effect. · Riboflavin (vitamin B2)
- organism
- Homo sapiens
- plain_language
- The genetic substitution weakens FMN binding.
- primary_references
- [musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372
- tissue_or_cell_type
- Purified recombinant enzyme; no intact tissue
- trigger_kind
- machinery_impairment Imported condition classification; unverified.
Riboflavin: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1206–1218
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. · source_derived_draft · unverified_draft
### b2-pnpo-r229w-fmn-affinity R229W PNPO had an FMN dissociation constant approximately 50-fold higher than wild type in apoenzyme fluorescence titrations. Condition category: machinery_impairment nutrient_topic: Riboflavin research collection; topical membership is not evidence of a direct dietary effect. plain_language: The genetic substitution weakens FMN binding. organism: Homo sapiens tissue_or_cell_type: Purified recombinant enzyme; no intact tissue experimental_model: Recombinant human wild-type and R229W PNPO; fluorescence titration, kinetics and 2.5-A mutant structure. limitations: Biochemical evidence does not establish a dietary threshold or supplementation benefit. exposure: Purified-enzyme assay cross_nutrient: A B6-activation disorder directly disrupts B2-cofactor binding. evidence_location: Results: Table 3 and Fig 1; Table 2 and Fig 2 [musayev2009] Molecular basis of reduced pyridoxine 5'-phosphate oxidase catalytic activity in neonatal epileptic encephalopathy disorder. (2009). https://pubmed.ncbi.nlm.nih.gov/19759001/ DOI: 10.1074/jbc.m109.038372
Complete structured claim and evidence
The events it takes part in
A mechanism often involves more than two components. These are the full events, with every participant and its role.
Situations it appears in
Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.
In the sources
Preserved passages that mention this component, quoted exactly. Open one to read it in context.
Open hypotheses
Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.
This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.