Component
Human methylmalonyl-CoA epimerase / MCEE
Human methylmalonyl-CoA epimerase / MCEE
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
Human MCEE interconverts methylmalonyl-CoA epimers, supplying the (R) form for MMUT; MCEE expression increased coupled succinate production.
Experimental context and source evidence
- cross_nutrient
- false
- evidence_location
- Full text Methods 2.6 and Results 3.6; Figure 5
- experimental_model
- Human fibroblast lysates overexpressing MCEE and/or MMUT
- exposure
- Radiolabeled propionyl-CoA; MCEE/MMUT expression and AdoCbl
- limitations
- Coupled labeled hydrolysis-product assay; MCEE being limiting here is not a universal in-vivo rate limitation.
- nutrient_topic
- Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
- organism
- Homo sapiens
- plain_language
- Human fibroblast assays showed why the epimerase step matters before the B12 enzyme.
- primary_references
- [heuberger-2019-mcee] Genetic, structural, and functional analysis of pathogenic variations causing methylmalonyl-CoA epimerase deficiency. (2019). https://pubmed.ncbi.nlm.nih.gov/30682498/ DOI: 10.1016/j.bbadis.2019.01.021
- tissue_or_cell_type
- Fibroblasts
Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1174–1186
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human fibroblast lysates overexpressing MCEE and/or MMUT · source_derived_draft · unverified_draft
### mcee-epimerizes-methylmalonyl-coa Human MCEE interconverts methylmalonyl-CoA epimers, supplying the (R) form for MMUT; MCEE expression increased coupled succinate production. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Human fibroblast assays showed why the epimerase step matters before the B12 enzyme. organism: Homo sapiens tissue_or_cell_type: Fibroblasts experimental_model: Human fibroblast lysates overexpressing MCEE and/or MMUT limitations: Coupled labeled hydrolysis-product assay; MCEE being limiting here is not a universal in-vivo rate limitation. exposure: Radiolabeled propionyl-CoA; MCEE/MMUT expression and AdoCbl cross_nutrient: false evidence_location: Full text Methods 2.6 and Results 3.6; Figure 5 [heuberger-2019-mcee] Genetic, structural, and functional analysis of pathogenic variations causing methylmalonyl-CoA epimerase deficiency. (2019). https://pubmed.ncbi.nlm.nih.gov/30682498/ DOI: 10.1016/j.bbadis.2019.01.021
Complete structured claim and evidence
Where it participates (unsigned role)
Human PCC supplies (S)-methylmalonyl-CoA by propionyl-CoA carboxylation upstream of the MCEE-MMUT sequence examined in fibroblast assays.
Experimental context and source evidence
- cross_nutrient
- true
- evidence_location
- Indexed primary abstract; Full text Methods 2.6 and Results 3.6; Figure 5
- experimental_model
- Human fibroblast PCC and coupled-pathway assays
- exposure
- Propionyl-CoA, ATP and bicarbonate in enzyme pathway
- limitations
- Pathway assignment combines human PCC characterization with coupled assays; it is not a simultaneous dietary biotin/B12 intervention.
- nutrient_topic
- Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin B12 (cobalamins)
- organism
- Homo sapiens
- plain_language
- Biotin-dependent PCC makes the precursor that must be rearranged before human MMUT can use B12 on it.
- primary_references
- [hsia-1979-pcc] Human propionyl CoA carboxylase: some properties of the partially purified enzyme in fibroblasts from controls and patients with propionic acidemia. (1979). https://pubmed.ncbi.nlm.nih.gov/481943/ DOI: 10.1203/00006450-197906000-00005 [heuberger-2019-mcee] Genetic, structural, and functional analysis of pathogenic variations causing methylmalonyl-CoA epimerase deficiency. (2019). https://pubmed.ncbi.nlm.nih.gov/30682498/ DOI: 10.1016/j.bbadis.2019.01.021
- tissue_or_cell_type
- Fibroblasts
Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1159–1172
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human fibroblast PCC and coupled-pathway assays · source_derived_draft · unverified_draft
### pcc-carboxylation-upstream-b12 Human PCC supplies (S)-methylmalonyl-CoA by propionyl-CoA carboxylation upstream of the MCEE-MMUT sequence examined in fibroblast assays. Condition category: normal nutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Biotin-dependent PCC makes the precursor that must be rearranged before human MMUT can use B12 on it. organism: Homo sapiens tissue_or_cell_type: Fibroblasts experimental_model: Human fibroblast PCC and coupled-pathway assays limitations: Pathway assignment combines human PCC characterization with coupled assays; it is not a simultaneous dietary biotin/B12 intervention. exposure: Propionyl-CoA, ATP and bicarbonate in enzyme pathway cross_nutrient: true evidence_location: Indexed primary abstract; Full text Methods 2.6 and Results 3.6; Figure 5 [hsia-1979-pcc] Human propionyl CoA carboxylase: some properties of the partially purified enzyme in fibroblasts from controls and patients with propionic acidemia. (1979). https://pubmed.ncbi.nlm.nih.gov/481943/ DOI: 10.1203/00006450-197906000-00005 [heuberger-2019-mcee] Genetic, structural, and functional analysis of pathogenic variations causing methylmalonyl-CoA epimerase deficiency. (2019). https://pubmed.ncbi.nlm.nih.gov/30682498/ DOI: 10.1016/j.bbadis.2019.01.021
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.