Beta-carotene oxygenase 1 / BCO1

evidence_span

{"source_cache": "artifacts/lycopene-research/24187135.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "cf8ce69a4772c58e274590a2e3f251bed46de77b4d844b54c98d39fcd27e3e91", "start_char": 0, "end_char": 1772, "text_sha256": "cf8ce69a4772c58e274590a2e3f251bed46de77b4d844b54c98d39fcd27e3e91"}

experimental_model

Purified recombinant human enzyme kinetics

exposure

Substrate panel; product chromatography

limitations

Activity in a purified enzyme system does not establish dominant in-vivo flux; acycloretinal is not retinal or vitamin A.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Human BCO1 expressed in E. coli

plain_language

This product lacks the ring of vitamin-A retinal; cleavage does not make lycopene a vitamin A source.

primary_references

[lycopene-p24187135] Substrate specificity of purified recombinant human β-carotene 15,15'-oxygenase (BCO1). (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.m113.507160

tissue_or_cell_type

Cell-free carotenoid cleavage

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 377–388

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human enzyme kinetics · source_derived_draft · unverified_draft

### lycopene-bco1-acycloretinal Purified recombinant human BCO1 generated acycloretinal from lycopene, with reported catalytic efficiency similar to beta-carotene. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: This product lacks the ring of vitamin-A retinal; cleavage does not make lycopene a vitamin A source. organism: Human BCO1 expressed in E. coli tissue_or_cell_type: Cell-free carotenoid cleavage experimental_model: Purified recombinant human enzyme kinetics limitations: Activity in a purified enzyme system does not establish dominant in-vivo flux; acycloretinal is not retinal or vitamin A. exposure: Substrate panel; product chromatography evidence_span: {"source_cache": "artifacts/lycopene-research/24187135.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "cf8ce69a4772c58e274590a2e3f251bed46de77b4d844b54c98d39fcd27e3e91", "start_char": 0, "end_char": 1772, "text_sha256": "cf8ce69a4772c58e274590a2e3f251bed46de77b4d844b54c98d39fcd27e3e91"} [lycopene-p24187135] Substrate specificity of purified recombinant human β-carotene 15,15'-oxygenase (BCO1). (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.m113.507160

evidence_span

{"source_cache": "artifacts/lycopene-research/11960992.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42dd2ebd13adbf84c3f6f89de7374995253ff8f433cc72f32191eceb3c7eb3a0", "start_char": 0, "end_char": 1324, "text_sha256": "42dd2ebd13adbf84c3f6f89de7374995253ff8f433cc72f32191eceb3c7eb3a0"}

experimental_model

Purified recombinant human enzyme substrate-specificity analysis

exposure

Carotenoid substrate panel

limitations

Abstract supports the reported ring requirement; it does not supply a lycopene-specific numerical detection limit.

nutrient_topic

Lycopene research collection; topical membership is not evidence of a direct dietary effect. · Lycopene

organism

Human BCO1 expressed in insect cells

plain_language

An earlier experiment proposed a substrate rule that the later lycopene result challenges.

primary_references

[lycopene-p11960992] Biochemical properties of purified recombinant human beta-carotene 15,15'-monooxygenase. (2002). https://pubmed.ncbi.nlm.nih.gov/11960992/ DOI: 10.1074/jbc.m202756200

tissue_or_cell_type

Cell-free enzyme assay

Lycopene: absorption, metabolism, nutrient connections and human outcomes (2026-09-17) · lines 390–401

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified recombinant human enzyme substrate-specificity analysis · source_derived_draft · unverified_draft

### lycopene-bco1-ring-rule The 2002 human BCO1 study concluded that efficient cleavage required at least one unsubstituted beta-ionone ring. Condition category: normal nutrient_topic: Lycopene research collection; topical membership is not evidence of a direct dietary effect. plain_language: An earlier experiment proposed a substrate rule that the later lycopene result challenges. organism: Human BCO1 expressed in insect cells tissue_or_cell_type: Cell-free enzyme assay experimental_model: Purified recombinant human enzyme substrate-specificity analysis limitations: Abstract supports the reported ring requirement; it does not supply a lycopene-specific numerical detection limit. exposure: Carotenoid substrate panel evidence_span: {"source_cache": "artifacts/lycopene-research/11960992.abstract.txt", "locator": "Primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "42dd2ebd13adbf84c3f6f89de7374995253ff8f433cc72f32191eceb3c7eb3a0", "start_char": 0, "end_char": 1324, "text_sha256": "42dd2ebd13adbf84c3f6f89de7374995253ff8f433cc72f32191eceb3c7eb3a0"} [lycopene-p11960992] Biochemical properties of purified recombinant human beta-carotene 15,15'-monooxygenase. (2002). https://pubmed.ncbi.nlm.nih.gov/11960992/ DOI: 10.1074/jbc.m202756200

evidence_location

Abstract

experimental_model

Purified human BCO1 expressed in E. coli; substrate incubations and HPLC.

exposure

Purified BCO1 and alpha-carotene concentration series.

limitations

Lower catalytic efficiency than beta-carotene under these assay conditions.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens protein expressed in Escherichia coli

outcome

Human BCO1 generated retinal from alpha-carotene in substrate assays.

plain_language

Alpha-carotene can feed retinal production.

primary_references

[va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

tissue_or_cell_type

Cell-free enzyme

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 145–157

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. · source_derived_draft · unverified_draft

### va-bco1-alpha-carotene Human BCO1 generated retinal from alpha-carotene in substrate assays. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Alpha-carotene can feed retinal production. organism: Homo sapiens protein expressed in Escherichia coli tissue_or_cell_type: Cell-free enzyme experimental_model: Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. limitations: Lower catalytic efficiency than beta-carotene under these assay conditions. exposure: Purified BCO1 and alpha-carotene concentration series. outcome: Human BCO1 generated retinal from alpha-carotene in substrate assays. evidence_location: Abstract [va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

evidence_location

Abstract

experimental_model

Purified human BCO1 expressed in E. coli; substrate incubations and HPLC.

exposure

Purified BCO1 and beta-cryptoxanthin concentration series.

limitations

Does not quantify competition with the BCO2 pathway in vivo.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens protein expressed in Escherichia coli

outcome

Human BCO1 generated retinal from beta-cryptoxanthin in substrate assays.

plain_language

This hydroxylated carotenoid also supplies retinal in vitro.

primary_references

[va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

tissue_or_cell_type

Cell-free enzyme

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 159–171

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. · source_derived_draft · unverified_draft

### va-bco1-beta-cryptoxanthin Human BCO1 generated retinal from beta-cryptoxanthin in substrate assays. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: This hydroxylated carotenoid also supplies retinal in vitro. organism: Homo sapiens protein expressed in Escherichia coli tissue_or_cell_type: Cell-free enzyme experimental_model: Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. limitations: Does not quantify competition with the BCO2 pathway in vivo. exposure: Purified BCO1 and beta-cryptoxanthin concentration series. outcome: Human BCO1 generated retinal from beta-cryptoxanthin in substrate assays. evidence_location: Abstract [va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

evidence_location

Figure 3

experimental_model

Purified human BCO1 expressed in E. coli; substrate incubations and HPLC.

exposure

20 micromolar beta-carotene, 500 ng enzyme/200 microliters, 37 C, 15 minutes.

limitations

Purified-enzyme rates do not determine dietary conversion efficiency.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens protein expressed in Escherichia coli

outcome

Purified human BCO1 cleaved all-trans-beta-carotene centrally to all-trans-retinal.

plain_language

BCO1 turns a carotenoid precursor into retinal.

primary_references

[va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

tissue_or_cell_type

Cell-free enzyme

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 131–143

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. · source_derived_draft · unverified_draft

### va-bco1-central-cleavage Purified human BCO1 cleaved all-trans-beta-carotene centrally to all-trans-retinal. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: BCO1 turns a carotenoid precursor into retinal. organism: Homo sapiens protein expressed in Escherichia coli tissue_or_cell_type: Cell-free enzyme experimental_model: Purified human BCO1 expressed in E. coli; substrate incubations and HPLC. limitations: Purified-enzyme rates do not determine dietary conversion efficiency. exposure: 20 micromolar beta-carotene, 500 ng enzyme/200 microliters, 37 C, 15 minutes. outcome: Purified human BCO1 cleaved all-trans-beta-carotene centrally to all-trans-retinal. evidence_location: Figure 3 [va-delasena-2013] Substrate specificity of purified recombinant human beta-carotene 15,15'-oxygenase (BCO1) (2013). https://pubmed.ncbi.nlm.nih.gov/24187135/ DOI: 10.1074/jbc.M113.507160

availability_state

machinery_impairment Imported condition classification; unverified.

cross_nutrient

Links enzyme-bound iron to vitamin A precursor processing.

evidence_location

Abstract

experimental_model

Site-directed mutant mouse BCO1; cleavage assays and protein-bound iron spectroscopy.

exposure

Individual alanine substitutions at conserved catalytic-site residues.

limitations

Coordination inferred from mutagenesis and iron measurements, not a dietary iron trial.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Mus musculus recombinant protein

outcome

Substitution of conserved histidines or Glu405 in mouse BCO1 abolished cleavage and reduced protein-bound iron.

plain_language

An intact iron-binding environment is necessary for this enzyme to work.

primary_references

[va-poliakov-2005] Key role of conserved histidines in recombinant mouse beta-carotene 15,15'-monooxygenase-1 activity (2005). https://pubmed.ncbi.nlm.nih.gov/15951442/ DOI: 10.1074/jbc.M500409200

tissue_or_cell_type

Cell-free protein

trigger_kind

machinery_impairment Imported condition classification; unverified.

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 217–230

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Site-directed mutant mouse BCO1; cleavage assays and protein-bound iron spectroscopy. · source_derived_draft · unverified_draft

### va-bco1-iron-binding-machinery Substitution of conserved histidines or Glu405 in mouse BCO1 abolished cleavage and reduced protein-bound iron. Condition category: machinery_impairment nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: An intact iron-binding environment is necessary for this enzyme to work. organism: Mus musculus recombinant protein tissue_or_cell_type: Cell-free protein experimental_model: Site-directed mutant mouse BCO1; cleavage assays and protein-bound iron spectroscopy. limitations: Coordination inferred from mutagenesis and iron measurements, not a dietary iron trial. exposure: Individual alanine substitutions at conserved catalytic-site residues. outcome: Substitution of conserved histidines or Glu405 in mouse BCO1 abolished cleavage and reduced protein-bound iron. evidence_location: Abstract cross_nutrient: Links enzyme-bound iron to vitamin A precursor processing. [va-poliakov-2005] Key role of conserved histidines in recombinant mouse beta-carotene 15,15'-monooxygenase-1 activity (2005). https://pubmed.ncbi.nlm.nih.gov/15951442/ DOI: 10.1074/jbc.M500409200

evidence_location

Abstract

experimental_model

Isx, Bco1, Bco2 and Scarb1 mouse mutants; promoter binding and controlled diets.

exposure

ISX binding and gene-expression experiments.

limitations

Does not establish a fixed carotenoid conversion ratio.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Mus musculus and promoter-binding preparations

outcome

ISX recognized upstream BCO1 regulatory motifs and repressed its expression.

plain_language

The same feedback factor limits the carotenoid-cleaving enzyme.

primary_references

[va-widjajaadhi-2015] A genetic dissection of intestinal fat-soluble vitamin and carotenoid absorption (2015). https://pmc.ncbi.nlm.nih.gov/articles/PMC4424956/ DOI: 10.1093/hmg/ddv072

tissue_or_cell_type

Intestinal epithelium

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 288–300

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Isx, Bco1, Bco2 and Scarb1 mouse mutants; promoter binding and controlled diets. · source_derived_draft · unverified_draft

### va-isx-bco1-repression ISX recognized upstream BCO1 regulatory motifs and repressed its expression. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: The same feedback factor limits the carotenoid-cleaving enzyme. organism: Mus musculus and promoter-binding preparations tissue_or_cell_type: Intestinal epithelium experimental_model: Isx, Bco1, Bco2 and Scarb1 mouse mutants; promoter binding and controlled diets. limitations: Does not establish a fixed carotenoid conversion ratio. exposure: ISX binding and gene-expression experiments. outcome: ISX recognized upstream BCO1 regulatory motifs and repressed its expression. evidence_location: Abstract [va-widjajaadhi-2015] A genetic dissection of intestinal fat-soluble vitamin and carotenoid absorption (2015). https://pmc.ncbi.nlm.nih.gov/articles/PMC4424956/ DOI: 10.1093/hmg/ddv072

evidence_location

Abstract

experimental_model

Recombinant human BCO1 with isotopically labeled oxygen and water.

exposure

18O2 versus H2-18O incubations with beta-carotene.

limitations

Reaction chemistry; no claim about clinical hypoxia or oxygen supplementation.

nutrient_topic

Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A

organism

Homo sapiens recombinant protein

outcome

Isotope tracing showed that oxygen incorporated into both BCO1-generated retinal products originated from molecular oxygen.

plain_language

BCO1 cleavage uses oxygen gas to make the two retinal aldehydes.

primary_references

[va-delasena-2014] The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase (2014). https://pubmed.ncbi.nlm.nih.gov/24668807/ DOI: 10.1074/jbc.M114.557710

tissue_or_cell_type

Cell-free enzyme

Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 173–185

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human BCO1 with isotopically labeled oxygen and water. · source_derived_draft · unverified_draft

### va-bco1-dioxygen-incorporation Isotope tracing showed that oxygen incorporated into both BCO1-generated retinal products originated from molecular oxygen. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: BCO1 cleavage uses oxygen gas to make the two retinal aldehydes. organism: Homo sapiens recombinant protein tissue_or_cell_type: Cell-free enzyme experimental_model: Recombinant human BCO1 with isotopically labeled oxygen and water. limitations: Reaction chemistry; no claim about clinical hypoxia or oxygen supplementation. exposure: 18O2 versus H2-18O incubations with beta-carotene. outcome: Isotope tracing showed that oxygen incorporated into both BCO1-generated retinal products originated from molecular oxygen. evidence_location: Abstract [va-delasena-2014] The human enzyme that converts dietary provitamin A carotenoids to vitamin A is a dioxygenase (2014). https://pubmed.ncbi.nlm.nih.gov/24668807/ DOI: 10.1074/jbc.M114.557710