Carotenoid Cleavage Dioxygenases of Crocus sativus L.
Carotenoid cleavage dioxygenases (CCDs) form a multienzyme family, the members of which are involved in the production of a diversity of apocarotenoids. The apocarotenoid module vital physiological and developmental processes in plants. This chapter deals
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Carotenoid Cleavage Dioxygenases of Crocus sativus L.
Abstract Carotenoid cleavage dioxygenases (CCDs) form a multienzyme family, the members of which are involved in the production of a diversity of apocarotenoids. The apocarotenoid module vital physiological and developmental processes in plants. This chapter deals with the different aspects of plant CCDs in general and C. sativus in particular such as structure and reaction mechanisms. Further, this chapter also discusses the role of CCDs in plants and their application in plant biotechnology. Keywords Carotenoid cleavage dioxygenase • Apocarotenoid • Saffron
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Introduction
Carotenoids are C40 isoprenoids and form one of the most diverse classes of natural compounds. They serve multitude of functions ranging from photosynthetic pigments to nutritional compounds and antioxidants. Carotenoids undergo a reaction involving incorporation of both oxygen atoms from molecular oxygen into their substrates across a double bond resulting in the production of two ketone- or aldehyde-containing cleavage products (Auldridge et al. 2006a, b). These cleavage products are known as apocarotenoids (Table 2.1). They are widespread in plant kingdom and carry out vital physiological and developmental processes in plants. They act as signaling molecules, growth regulators, pollinator attractants, and predator repellents and also provide some plants with competitive advantage over others (Bouvier et al. 2005a, b). In recent years, a number of enzymes involved in the production of apocarotenoids have been identified and characterized across plant kingdom. All of these belong to a family of enzymes called carotenoid cleavage dioxygenases (CCDs). These enzymes are promiscuous as far as their substrate specificity is concerned but show high regio- and stereospecificity for the double bonds they cleave (Huang et al. 2009). The first enzyme found to precisely cleave carotenoids, viviparous14 (VP14), was recognized by the investigation of viviparous abscisic acid-deficient mutant of maize
© Springer Nature Singapore Pte Ltd. 2016 S.A. Baba, N. Ashraf, Apocarotenoids of Crocus sativus L: From biosynthesis to pharmacology, SpringerBriefs in Plant Science, DOI 10.1007/978-981-10-1899-2_2
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Carotenoid Cleavage Dioxygenases of Crocus sativus L.
Table 2.1 Some important plant CCDs and their apocarotenoids Name of the plant Bixa
CCD BoCCD4, BoCCD1
Crocus sativus
CsCCd4a, CsCCD4b CsCCD1 CsCCD2 CmCCD4a, CmCCD4b PhCCD1 LeCCD1a, LeCCD1b
Chrysanthemum morifolium Petunia hybrida Lycopersicon esculentum Vitis vinifera Rosa damascena Cucumis melo
Osmanthus fragrans Fragaria ananassa Malus domestica Arabidopsis thaliana
VvCCD1, VvCCD4, RdCCD4 CmCCD1
OfCCD1 FaCCD1 MdCCD4 AtCCD4, AtCCD7, AtCCD8
Cleavage products Bixin, (9′Z)-apo-6′-lycopenoate, methyl (9′Z)-6′-oxo 6,6′-diapocarotenoate, and methyl (all-E)-8′-apo-b-caroten-8′-oate β-Ionone Crocin β-Ionone β-Ionone Geranylacetone Pseudoionone α- and β-ionone Pseudoionone, β-ionone, 3-hydroxy-β-ionone, geranylacetone β-ionone, grasshopp
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