370
M. C. Deprá et al.
geranyl pyrophosphate, farnesyl pyrophosphate or geranylgeranyl pyrophosphate,
which are the precursors of mono-, di-, and tri-terpenes and carotenoids (Hunter
2007; Lemoine and Schoefs 2010). Farnesyl pyrophosphate and geranylgeranyl
pyrophosphate are the immediate forerunners of C30 and C40 carotenoids (Lee and
Schmidt-Dannert 2002; Lu and Li 2008).
Through the head-to-tail condensation of two geranylgeranyl pyrophosphate
molecules, the phytoene (C40) is obtained. In this process, two diphosphate groups
are rejected, being catalyzed by phytoene synthase (PSY) (Lemoine and Schoefs
2010). PSY is among the more important enzymes for carotenoid biosynthesis in
photosynthetic organisms and can be controlled by environmental stresses (Bertrand
2010; Nisar et al. 2015). The enzymes phytoene desaturase (PDS) and ζ-carotene
desaturase catalyze successive desaturation reactions of phytoene, enhancing the
number of conjugated carbon–carbon double bonds and ensue in the formation of
the first phytofluene, zeta-carotene (ζ-carotene), neurosporene and finally the first
colored carotenoid, lycopene is formed (Varela et al. 2015).
The formation of α and β-carotene occurs after two cyclization reactions of biosynthesized lycopene. The α-carotene is transformed in two steps to lutein, while the
β-carotene can then be transformed to zeaxanthin by two successive hydroxylation
steps (Paniagua-Michel et al. 2012).
Astaxanthin synthesis can occur by the oxidation of β-carotene, having echinenone, canthaxanthin and phoenicoxanthin as intermediates or by the hydroxylation
of β-carotene, having β-cryptoxanthin, zeaxanthin and adonixanthin as intermediates
(Lemoine and Schoefs 2010).
15.3.2 Microalgae Phycobiliproteins Production
Among commercially important pigments of microalgae, phycobiliproteins stand out
not only for their commercial value but also because these pigments are exclusive of
some microalgae classes (Cyanophyta, Rhodophyta, Cryptophyta, and Glaucophyta)
(Guiry and Guiry 2019). In addition, there are no existing derived counterparts of
the synthetic route (Klein and Buchholz 2013).
The initial step of phycobiliproteins biosynthesis is the cleavage of heme macrocycle by the action of heme oxygenase (HO), to afford the first linear molecule
biliverdin IXα (BV) (Fig. 15.6) (Dammeyer and Frankenberg-Dinkel 2008). A
complete heme oxygenase catalytic cycle requires a total of seven electrons and
three molecules of molecular oxygen to yield biliverdin IXα (Wilks 2002).
Then, the enzyme biliverdin reductase (BvdR) reduces the methine bridge between
ring B and C of biliverdin IXα (BV) resulting in the formation of bilirubin IXα (BR) in
the presence of cofactor NADH and NADPH. Biliverdin reductase (BvdR) displays
a high substrate specificity to prevent cross-reactions with other bilin metabolites
like phycocyanobilin (PCB) and phycoerythrobilin (PEB) that occur in the same
organisms (Sugishima et al. 2005).
M. C. Deprá et al.
geranyl pyrophosphate, farnesyl pyrophosphate or geranylgeranyl pyrophosphate,
which are the precursors of mono-, di-, and tri-terpenes and carotenoids (Hunter
2007; Lemoine and Schoefs 2010). Farnesyl pyrophosphate and geranylgeranyl
pyrophosphate are the immediate forerunners of C30 and C40 carotenoids (Lee and
Schmidt-Dannert 2002; Lu and Li 2008).
Through the head-to-tail condensation of two geranylgeranyl pyrophosphate
molecules, the phytoene (C40) is obtained. In this process, two diphosphate groups
are rejected, being catalyzed by phytoene synthase (PSY) (Lemoine and Schoefs
2010). PSY is among the more important enzymes for carotenoid biosynthesis in
photosynthetic organisms and can be controlled by environmental stresses (Bertrand
2010; Nisar et al. 2015). The enzymes phytoene desaturase (PDS) and ζ-carotene
desaturase catalyze successive desaturation reactions of phytoene, enhancing the
number of conjugated carbon–carbon double bonds and ensue in the formation of
the first phytofluene, zeta-carotene (ζ-carotene), neurosporene and finally the first
colored carotenoid, lycopene is formed (Varela et al. 2015).
The formation of α and β-carotene occurs after two cyclization reactions of biosynthesized lycopene. The α-carotene is transformed in two steps to lutein, while the
β-carotene can then be transformed to zeaxanthin by two successive hydroxylation
steps (Paniagua-Michel et al. 2012).
Astaxanthin synthesis can occur by the oxidation of β-carotene, having echinenone, canthaxanthin and phoenicoxanthin as intermediates or by the hydroxylation
of β-carotene, having β-cryptoxanthin, zeaxanthin and adonixanthin as intermediates
(Lemoine and Schoefs 2010).
15.3.2 Microalgae Phycobiliproteins Production
Among commercially important pigments of microalgae, phycobiliproteins stand out
not only for their commercial value but also because these pigments are exclusive of
some microalgae classes (Cyanophyta, Rhodophyta, Cryptophyta, and Glaucophyta)
(Guiry and Guiry 2019). In addition, there are no existing derived counterparts of
the synthetic route (Klein and Buchholz 2013).
The initial step of phycobiliproteins biosynthesis is the cleavage of heme macrocycle by the action of heme oxygenase (HO), to afford the first linear molecule
biliverdin IXα (BV) (Fig. 15.6) (Dammeyer and Frankenberg-Dinkel 2008). A
complete heme oxygenase catalytic cycle requires a total of seven electrons and
three molecules of molecular oxygen to yield biliverdin IXα (Wilks 2002).
Then, the enzyme biliverdin reductase (BvdR) reduces the methine bridge between
ring B and C of biliverdin IXα (BV) resulting in the formation of bilirubin IXα (BR) in
the presence of cofactor NADH and NADPH. Biliverdin reductase (BvdR) displays
a high substrate specificity to prevent cross-reactions with other bilin metabolites
like phycocyanobilin (PCB) and phycoerythrobilin (PEB) that occur in the same
organisms (Sugishima et al. 2005).