1 Chlorophylls in Microalgae: Occurrence …
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protochlorophyllide reduction in the absence of light of most algae correlates with
the presence of the chlB, chlL, and chlN genes. It is accepted that these genes encode
all of the subunits of DPOR in oxygenic-evolving photosynthetic prokaryotes and
eukaryotes (Galova et al. 2008).
1.3.1 Chlorophyll b
In green algae, both Chl a and Chl b have their functions in the photosynthetic process,
in the light reactions. While Chl a is present in the core of antenna and reaction
centers, and is important for the light-harvesting and electron transfer (Larkum 2016),
Chl b is associated with PSII antenna (Pocock et al. 2007, Szyszka et al. 2007), mostly
present in the peripheral antenna complexes (Green and Durnford 1996, La Roche
et al. 1996), and besides light harvesting it acts in the stabilization of the peripheral
antenna complexes. The Chl a:Chl b is usually 3:1 in green algae, but Chl b can
increase in shade adapted green algae, decreasing the ratio to 1.8–2.2 (Falkowski
and Owens 1980). Chlorophyll b is the second most abundant among the chlorophyll
pigment in nature and is found in the light-harvesting apparatus, with important
function as accessory pigment (Cahoon and Timko 2003).
Figure 1.4 shows the structure of Chl a and Chl b. Chlorophyll b that has a molecular weight of 907 g/mol differs from Chl a (M.W. 839 g/mol) in the third position
of its chlorin ring, which is a methyl group in Chl a and an aldehyde (formyl) group
in Chl b. According to Rüdiger (2002) Chl a and Chl b follow the same biosynthetic pathway and the difference is only a step, the transformation of the 7-methyl
group to the 7-formyl group. Experiments performed with
14 C on Chl a and Chl b
in Chlorella pyrenoidosa and Scenedesmus obliquus by Blass et al. (1959) showed
that Chl a may be a precursor of Chl b. It has also been shown that Chl a appears
Fig. 1.4 Schematic representation of Chlorophyll a and Chlorophyll b. In Chl a the side group in
the third carbon is a methyl group (-CH3) while in Chl b it is an aldehyde group (-CHO)
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protochlorophyllide reduction in the absence of light of most algae correlates with
the presence of the chlB, chlL, and chlN genes. It is accepted that these genes encode
all of the subunits of DPOR in oxygenic-evolving photosynthetic prokaryotes and
eukaryotes (Galova et al. 2008).
1.3.1 Chlorophyll b
In green algae, both Chl a and Chl b have their functions in the photosynthetic process,
in the light reactions. While Chl a is present in the core of antenna and reaction
centers, and is important for the light-harvesting and electron transfer (Larkum 2016),
Chl b is associated with PSII antenna (Pocock et al. 2007, Szyszka et al. 2007), mostly
present in the peripheral antenna complexes (Green and Durnford 1996, La Roche
et al. 1996), and besides light harvesting it acts in the stabilization of the peripheral
antenna complexes. The Chl a:Chl b is usually 3:1 in green algae, but Chl b can
increase in shade adapted green algae, decreasing the ratio to 1.8–2.2 (Falkowski
and Owens 1980). Chlorophyll b is the second most abundant among the chlorophyll
pigment in nature and is found in the light-harvesting apparatus, with important
function as accessory pigment (Cahoon and Timko 2003).
Figure 1.4 shows the structure of Chl a and Chl b. Chlorophyll b that has a molecular weight of 907 g/mol differs from Chl a (M.W. 839 g/mol) in the third position
of its chlorin ring, which is a methyl group in Chl a and an aldehyde (formyl) group
in Chl b. According to Rüdiger (2002) Chl a and Chl b follow the same biosynthetic pathway and the difference is only a step, the transformation of the 7-methyl
group to the 7-formyl group. Experiments performed with
14 C on Chl a and Chl b
in Chlorella pyrenoidosa and Scenedesmus obliquus by Blass et al. (1959) showed
that Chl a may be a precursor of Chl b. It has also been shown that Chl a appears
Fig. 1.4 Schematic representation of Chlorophyll a and Chlorophyll b. In Chl a the side group in
the third carbon is a methyl group (-CH3) while in Chl b it is an aldehyde group (-CHO)