Component

Human D-aspartate oxidase / DDO

Context-specific entity; species, compartment and exposure are stated on each claim.

11 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 it acts on

  1. Subcellular fractionation localized D-aspartate oxidase activity to peroxisomes in human liver.

    Human D-aspartate oxidase / DDO → Human liver peroxisomes source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Human liver fractionation; rat liver also studied.
    limitations
    The study did not find a significant oxidase deficiency in its Zellweger liver samples; peroxisomal disease is not automatically DDO deficiency.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Clearance chemistry is organized within a cellular compartment.
    primary_references
    D-aspartate oxidase, a peroxisomal enzyme in liver of rat and man. · 1991 · https://pubmed.ncbi.nlm.nih.gov/1991137/ · DOI 10.1016/0304-4165(91)90203-s

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 88–94

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human liver fractionation; rat liver also studied. · source_derived_draft · unverified_draft

    ## d-aspartate-ddo-peroxisome Clearance chemistry is organized within a cellular compartment. Subcellular fractionation localized D-aspartate oxidase activity to peroxisomes in human liver. Model: Human liver fractionation; rat liver also studied. Limitations: The study did not find a significant oxidase deficiency in its Zellweger liver samples; peroxisomal disease is not automatically DDO deficiency. Evidence access: Primary abstract D-aspartate oxidase, a peroxisomal enzyme in liver of rat and man. · 1991 · https://pubmed.ncbi.nlm.nih.gov/1991137/ · DOI 10.1016/0304-4165(91)90203-s
    Complete structured claim and evidence

  2. Purified human, rat and mouse DDO differed in kinetic and inhibitor-binding properties.

    Human D-aspartate oxidase / DDO → Mouse D-aspartate oxidase / Ddo source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Comparative recombinant enzyme assays and structural models.
    limitations
    Rodent efficacy is not a measured human effect.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    A compound that changes rodent clearance may act differently on the human enzyme.
    primary_references
    Characterization of the enzymatic and structural properties of human D-aspartate oxidase and comparison with those of the rat and mouse enzymes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25747990/ · DOI 10.1248/bpb.b14-00690

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 128–134

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Comparative recombinant enzyme assays and structural models. · source_derived_draft · unverified_draft

    ## d-aspartate-ddo-species A compound that changes rodent clearance may act differently on the human enzyme. Purified human, rat and mouse DDO differed in kinetic and inhibitor-binding properties. Model: Comparative recombinant enzyme assays and structural models. Limitations: Rodent efficacy is not a measured human effect. Evidence access: Primary abstract Characterization of the enzymatic and structural properties of human D-aspartate oxidase and comparison with those of the rat and mouse enzymes. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25747990/ · DOI 10.1248/bpb.b14-00690
    Complete structured claim and evidence

  3. Purified human DDO-1 oxidized D-aspartate; the reported Km was 2.7 mM and kcat 52.5 per second.

    Human D-aspartate oxidase / DDO → D-Aspartate source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Recombinant human 341-residue DDO-1.
    limitations
    Assay kinetic constants are not clinical plasma targets; do not assign these activities to the alternatively spliced deletion isoform.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Humans have an enzyme that breaks down D-aspartate.
    primary_references
    Structural and functional characterization of the human brain D-aspartate oxidase. · 1997 · https://pubmed.ncbi.nlm.nih.gov/9163533/ · DOI 10.1093/oxfordjournals.jbchem.a021655

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 72–78

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Recombinant human 341-residue DDO-1. · source_derived_draft · unverified_draft

    ## d-aspartate-human-ddo-activity Humans have an enzyme that breaks down D-aspartate. Purified human DDO-1 oxidized D-aspartate; the reported Km was 2.7 mM and kcat 52.5 per second. Model: Recombinant human 341-residue DDO-1. Limitations: Assay kinetic constants are not clinical plasma targets; do not assign these activities to the alternatively spliced deletion isoform. Evidence access: Primary abstract Structural and functional characterization of the human brain D-aspartate oxidase. · 1997 · https://pubmed.ncbi.nlm.nih.gov/9163533/ · DOI 10.1093/oxfordjournals.jbchem.a021655
    Complete structured claim and evidence

  4. Human DDO-1 also oxidized N-methyl-D-aspartate, with reported Km 6.8 mM and kcat 37.7 per second.

    Human D-aspartate oxidase / DDO → N-Methyl-D-aspartate source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Purified recombinant human DDO-1.
    limitations
    Does not establish endogenous NMDA synthesis or justify conflating NMDA with D-aspartate.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    The enzyme accepts a related chemical that is distinct from the NMDA receptor.
    primary_references
    Structural and functional characterization of the human brain D-aspartate oxidase. · 1997 · https://pubmed.ncbi.nlm.nih.gov/9163533/ · DOI 10.1093/oxfordjournals.jbchem.a021655

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 80–86

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified recombinant human DDO-1. · source_derived_draft · unverified_draft

    ## d-aspartate-human-ddo-nmda The enzyme accepts a related chemical that is distinct from the NMDA receptor. Human DDO-1 also oxidized N-methyl-D-aspartate, with reported Km 6.8 mM and kcat 37.7 per second. Model: Purified recombinant human DDO-1. Limitations: Does not establish endogenous NMDA synthesis or justify conflating NMDA with D-aspartate. Evidence access: Primary abstract Structural and functional characterization of the human brain D-aspartate oxidase. · 1997 · https://pubmed.ncbi.nlm.nih.gov/9163533/ · DOI 10.1093/oxfordjournals.jbchem.a021655
    Complete structured claim and evidence

What acts on it

  1. Human D-aspartate oxidase structure and kinetics showed a FAD-containing enzyme with higher FAD affinity than human D-amino-acid oxidase.

    FAD → Human D-aspartate oxidase / DDO source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary abstract
    experimental_model
    Purified human DASPO/DDO structural and kinetic comparison with human DAO.
    limitations
    Does not show that dietary riboflavin limits DDO in vivo or that DAO inhibitors also inhibit DDO.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Two similarly named enzymes handle different D-amino-acid pathways and bind their cofactor differently.
    primary_references
    Structure and kinetic properties of human d-aspartate oxidase, the enzyme-controlling d-aspartate levels in brain. · 2020 · https://pubmed.ncbi.nlm.nih.gov/31914658/ · DOI 10.1096/fj.201901703R

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 96–102

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified human DASPO/DDO structural and kinetic comparison with human DAO. · source_derived_draft · unverified_draft

    ## d-aspartate-ddo-fad Two similarly named enzymes handle different D-amino-acid pathways and bind their cofactor differently. Human D-aspartate oxidase structure and kinetics showed a FAD-containing enzyme with higher FAD affinity than human D-amino-acid oxidase. Model: Purified human DASPO/DDO structural and kinetic comparison with human DAO. Limitations: Does not show that dietary riboflavin limits DDO in vivo or that DAO inhibitors also inhibit DDO. Evidence access: Primary abstract Structure and kinetic properties of human d-aspartate oxidase, the enzyme-controlling d-aspartate levels in brain. · 2020 · https://pubmed.ncbi.nlm.nih.gov/31914658/ · DOI 10.1096/fj.201901703R
    Complete structured claim and evidence

  2. Olanzapine inhibited recombinant human DDO at an IC50 near 23 micromolar under both 4 and 100 micromolar FAD conditions; clozapine did not inhibit the tested enzyme.

    Olanzapine → Human D-aspartate oxidase / DDO source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary full text
    experimental_model
    Purified human DDO drug concentration-response assay.
    limitations
    Biochemical potency is not proof of clinically relevant brain inhibition or a reason to change treatment.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Two drugs differed at a D-aspartate-clearing enzyme.
    primary_references
    Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28393897/ · DOI 10.1038/srep46288

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 264–270

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified human DDO drug concentration-response assay. · source_derived_draft · unverified_draft

    ## d-aspartate-olanzapine-human-ddo Two drugs differed at a D-aspartate-clearing enzyme. Olanzapine inhibited recombinant human DDO at an IC50 near 23 micromolar under both 4 and 100 micromolar FAD conditions; clozapine did not inhibit the tested enzyme. Model: Purified human DDO drug concentration-response assay. Limitations: Biochemical potency is not proof of clinically relevant brain inhibition or a reason to change treatment. Evidence access: Primary full text Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28393897/ · DOI 10.1038/srep46288
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. DDO mRNA was higher in the study prefrontal samples from people with schizophrenia than controls.

    Schizophrenia diagnosis in postmortem comparisons → Human prefrontal DDO transcript abundance source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    evidence_access
    Primary full text
    experimental_model
    Human postmortem prefrontal cortex; 10 schizophrenia and 11 control samples.
    limitations
    Observational, small cohort; transcript abundance is not enzyme activity and does not establish causation.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    One brain-sample study found more transcript for the clearing enzyme.
    primary_references
    A role for D-aspartate oxidase in schizophrenia and in schizophrenia-related symptoms induced by phencyclidine in mice. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25689573/ · DOI 10.1038/tp.2015.2
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 288–294

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human postmortem prefrontal cortex; 10 schizophrenia and 11 control samples. · source_derived_draft · unverified_draft

    ## d-aspartate-ddo-transcript-increase One brain-sample study found more transcript for the clearing enzyme. DDO mRNA was higher in the study prefrontal samples from people with schizophrenia than controls. Model: Human postmortem prefrontal cortex; 10 schizophrenia and 11 control samples. Limitations: Observational, small cohort; transcript abundance is not enzyme activity and does not establish causation. Evidence access: Primary full text A role for D-aspartate oxidase in schizophrenia and in schizophrenia-related symptoms induced by phencyclidine in mice. · 2015 · https://pubmed.ncbi.nlm.nih.gov/25689573/ · DOI 10.1038/tp.2015.2
    Complete structured claim and evidence

  2. A later postmortem study found no significant schizophrenia-related difference in DDO transcription or methylation despite higher DDO activity in dorsolateral prefrontal cortex.

    Schizophrenia diagnosis in postmortem comparisons → Human prefrontal DDO transcript abundance source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    evidence_access
    Primary full text
    experimental_model
    Human DLPFC and hippocampal tissue comparison.
    limitations
    A null test does not prove equality; cohort and tissue handling can differ.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Enzyme activity changed without a detected transcript change.
    primary_references
    Decreased free d-aspartate levels are linked to enhanced d-aspartate oxidase activity in the dorsolateral prefrontal cortex of schizophrenia patients. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28560262/ · DOI 10.1038/s41537-017-0015-7
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 296–302

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human DLPFC and hippocampal tissue comparison. · source_derived_draft · unverified_draft

    ## d-aspartate-ddo-transcript-null Enzyme activity changed without a detected transcript change. A later postmortem study found no significant schizophrenia-related difference in DDO transcription or methylation despite higher DDO activity in dorsolateral prefrontal cortex. Model: Human DLPFC and hippocampal tissue comparison. Limitations: A null test does not prove equality; cohort and tissue handling can differ. Evidence access: Primary full text Decreased free d-aspartate levels are linked to enhanced d-aspartate oxidase activity in the dorsolateral prefrontal cortex of schizophrenia patients. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28560262/ · DOI 10.1038/s41537-017-0015-7
    Complete structured claim and evidence

  3. An expanded regional methylation/expression analysis found brain-region differences but no significant diagnostic association for DDO expression or methylation.

    Schizophrenia diagnosis in postmortem comparisons → Human prefrontal DDO transcript abundance source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    evidence_access
    Primary full text
    experimental_model
    Human postmortem DLPFC, hippocampus and cerebellum; epiallele analysis.
    limitations
    Overlaps the earlier research group and reuses previously reported regional methylation data; not an independent replication of every measurement.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Regional identity mattered more than diagnosis in this analysis.
    primary_references
    DNA methylation landscape of the genes regulating D-serine and D-aspartate metabolism in post-mortem brain from controls and subjects with schizophrenia. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29976992/ · DOI 10.1038/s41598-018-28332-x
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 312–318

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human postmortem DLPFC, hippocampus and cerebellum; epiallele analysis. · source_derived_draft · unverified_draft

    ## d-aspartate-human-epialleles Regional identity mattered more than diagnosis in this analysis. An expanded regional methylation/expression analysis found brain-region differences but no significant diagnostic association for DDO expression or methylation. Model: Human postmortem DLPFC, hippocampus and cerebellum; epiallele analysis. Limitations: Overlaps the earlier research group and reuses previously reported regional methylation data; not an independent replication of every measurement. Evidence access: Primary full text DNA methylation landscape of the genes regulating D-serine and D-aspartate metabolism in post-mortem brain from controls and subjects with schizophrenia. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29976992/ · DOI 10.1038/s41598-018-28332-x
    Complete structured claim and evidence

  4. Schizophrenia DLPFC samples had approximately 30% lower free D-aspartate and 25% higher DDO activity; the D-aspartate reduction was not detected in hippocampus.

    Schizophrenia diagnosis in postmortem comparisons → Free D-aspartate in human dorsolateral prefrontal cortex source_derived_draftungraded
    Experimental context and source evidence
    availability_state
    biomarker_context Imported condition classification; unverified.
    evidence_access
    Primary full text
    experimental_model
    Human postmortem case-control study.
    limitations
    Not a dietary deficiency diagnosis, proof of disease cause, or a supplementation trial.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    The measured difference was local to a brain region.
    primary_references
    Decreased free d-aspartate levels are linked to enhanced d-aspartate oxidase activity in the dorsolateral prefrontal cortex of schizophrenia patients. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28560262/ · DOI 10.1038/s41537-017-0015-7
    trigger_kind
    biomarker_context Imported condition classification; unverified.

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 304–310

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human postmortem case-control study. · source_derived_draft · unverified_draft

    ## d-aspartate-human-low-dasp The measured difference was local to a brain region. Schizophrenia DLPFC samples had approximately 30% lower free D-aspartate and 25% higher DDO activity; the D-aspartate reduction was not detected in hippocampus. Model: Human postmortem case-control study. Limitations: Not a dietary deficiency diagnosis, proof of disease cause, or a supplementation trial. Evidence access: Primary full text Decreased free d-aspartate levels are linked to enhanced d-aspartate oxidase activity in the dorsolateral prefrontal cortex of schizophrenia patients. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28560262/ · DOI 10.1038/s41537-017-0015-7
    Complete structured claim and evidence

  5. Lowering assay FAD from 100 to 4 micromolar shifted olanzapine IC50 at mouse DDO from about 5.6 to 1.4 micromolar; the human enzyme did not show this potency shift.

    FAD → Olanzapine inhibition potency at mouse DDO source_derived_draftungraded
    Experimental context and source evidence
    evidence_access
    Primary full text
    experimental_model
    Recombinant mouse versus human DDO assays.
    limitations
    This is not an observed dietary riboflavin-drug interaction in people.
    nutrient_topic
    D-Aspartate collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · D-Aspartate
    plain_language
    Cofactor conditions altered the mouse drug-enzyme interaction.
    primary_references
    Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28393897/ · DOI 10.1038/srep46288

    D-Aspartate: synthesis, clearance, neural and endocrine mechanisms (2026-09-19) · lines 272–278

    AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Recombinant mouse versus human DDO assays. · source_derived_draft · unverified_draft

    ## d-aspartate-olanzapine-fad-species Cofactor conditions altered the mouse drug-enzyme interaction. Lowering assay FAD from 100 to 4 micromolar shifted olanzapine IC50 at mouse DDO from about 5.6 to 1.4 micromolar; the human enzyme did not show this potency shift. Model: Recombinant mouse versus human DDO assays. Limitations: This is not an observed dietary riboflavin-drug interaction in people. Evidence access: Primary full text Olanzapine, but not clozapine, increases glutamate release in the prefrontal cortex of freely moving mice by inhibiting D-aspartate oxidase activity. · 2017 · https://pubmed.ncbi.nlm.nih.gov/28393897/ · DOI 10.1038/srep46288
    Complete structured claim and evidence

In the sources

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