ABSTRACT
Carotenoids are comprised by numerous coloured compounds containing a C40-skeleton characterized by the presence of conjugated double bonds. During biosynthesis, they undergo various chemical changes giving rise to an array of intermediate products known as apocarotenoids, which are essential for the primary and secondary metabolism of living organisms. Apocarotenoids are generally catalyzed by carotenoid cleavage oxygenases (CCOs), which can cleave them in different sites according to the type of enzyme. The resulting apocarotenoids are grouped into pigments, hormones, signals, volatiles, and aromas.
CCOs enzymes can be mono- or di-oxygenases. Animal monooxygenases are called CMOs or BMOs. Microorganisms CCOs include ACO, NSC, CCD, CarT, CarX, and TSP3. Plant CCOs are regularly known as CCDs. According to their cleaving position or substrate of preference, they have been classified into 6 subfamilies: CCD1, CCD2, CCD4, CCD7, CCD8, and NECDs. The study of the synthesis and function of apocarotenoids has been increasingly surprising and new ones are continuously being discovered, along with the catalytic enzymes involved in their production. Research perspectives on the biogenesis and functions of these molecules are becoming extremely attractive and exciting in all taxa.
