title: Importance of β,β-carotene 15,15'-monooxygenase 1 (BCMO1) and β,β-carotene 9',10'-dioxygenase 2 (BCDO2) in nutrition and health.
abstract: In humans, varying amounts of absorbed β-carotene are oxidatively cleaved by the enzyme β,β-carotene 15,15'-monooxygenase 1 (BCMO1) into two molecules of all-trans-retinal. The other carotenoid cleavage enzyme β,β-carotene 9',10'-dioxygenase (BCDO2) cleaves β-carotene at the 9',10' double bond forming β-apo-10'-carotenal and β-ionone. Although the contribution of BCDO2 to vitamin A formation has long been debated, BCMO1 is currently considered the key enzyme for retinoid metabolism. Furthermore, BCMO1 has limited enzyme activity towards carotenoids other than provitamin A carotenoids, whereas BCDO2 exhibits a broader specificity. Both enzymes are located at different sites within the cell, with BCMO1 being a cytosolic protein and BCDO2 being located in the mitochondria. Expression of BCMO1 in tissues other than the intestine has recently revealed its function for tissue-specific retinoid metabolism with importance in embryogenesis and lipid metabolism. On the other hand, biological activity of BCDO2 metabolites has been shown to be important in protecting against carotenoid-induced mitochondrial dysfunction. Single-nucleotide polymorphisms (SNPs) such as R267S and A379V in BCMO1 can partly explain inter-individual variations observed in carotenoid metabolism. Advancing knowledge about the physiological role of these two enzymes will contribute to understanding the importance of carotenoids in health and disease.
authors.affiliation: Newcastle University, Human Nutrition Research Centre, Institute for Ageing and Health, School of Agriculture, Food and Rural Development, Newcastle upon Tyne, UK. georg.lietz@ncl.ac.uk
authors.forename: Georg
authors.initials: G
authors.lastname: Lietz
authors.forename: Anthony
authors.initials: A
authors.lastname: Oxley
authors.forename: Christine
authors.initials: C
authors.lastname: Boesch-Saadatmandi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D002338:Carotenoids / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D049308:Dioxygenases; D044943:Fatty Acid Desaturases / Q000502:physiology*; D014644:Genetic Variation; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D009747:Nutritional Physiological Phenomena; D009928:Organ Specificity; D020641:Polymorphism, Single Nucleotide; D012176:Retinoids / Q000378:metabolism; D013379:Substrate Specificity; D050559:beta-Carotene 15,15'-Monooxygenase / Q000502:physiology*
chemical_list: D012176:Retinoids; D002338:Carotenoids; D049308:Dioxygenases; D044943:Fatty Acid Desaturases; C506534:BCO2 protein, human; C493358:BCO1 protein, human; D050559:beta-Carotene 15,15'-Monooxygenase