Pure and Applied Chemistry

Abstract: The enzyme that catalyzes the central cleavage of β-carotene is an iron monooxygenase. The protein was isolated from chicken intestinal mucosa and overexpressed in two different cell lines. Inductively coupled plasma (ICP) emission analysis revealed that the hydrophobic 60.3-kDa enzyme contains one iron/mole protein. The substrate specificity was investigated, and the reaction mechanism elucidated incubating α-carotene in the presence of highly enriched ¹⁷O₂ and H₂¹⁸O. A supramolecular enzyme model was synthesized, binding carotenoids K_a > 106 mol_-1, which mimics the regiospecific enzymatic cleavage of carotenoids.