1 Chlorophylls in Microalgae: Occurrence …
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f (Allakhverdiev et al. 2016). Chl f has been shown to have absorption peak at
about 706 nm and a maximum fluorescence emission at 722 nm at room temperature
in methanol, making it the most red-shifted chlorophyll discovered to date (Chen
et al. 2010). The photophysical and photochemical functions of Chl f are still poorly
known (Li et al. 2012). The photophysical and photochemical properties and function of Chl f are being now investigated (Li et al. 2012, Gan et al. 2014, Ho 2018,
Kurashov et al. 2019).
1.3 Biosynthesis of Chlorophylls: A Short Overview
The pathways of chlorophyll a biosynthesis were based in experiments with leaves
(Smith 1948), a mutant of Chlorella that accumulated protoprophyrin IX but not
chlorophyll (Granick 1948a), and additional observations with heme (Fe protoporphyrin IX) (Shemin and Wittenberg 1951). In details, the history and the pigment
biosynthesis can be found in Marks (1966) and Bogorad (1967). Hendry and Jones
(1980) present a detailed study comparing heme and chlorophylls, with the biosynthetic pathways of tetrapyrroles and their natural occurrence. A more recent text on
the biochemistry and regulation of chlorophyll biosynthesis can be found in Cahoon
and Timko (2003).
The first indication of relation between the structure of the green pigment of plants
(chlorophyll) and heme, the prosthetic group of the red blood pigment hemoglobin,
dates back to 1880, as reported in Marks (1966). In spite of the differences in these two
molecules (chlorophylls and heme), the arrangement of their side chains is identical.
Their structural similarity has generated the idea that the biosynthesis of heme and
chlorophylls could have similar pathways. This was further confirmed by Granick and
co-workers (Granick 1948a, 1948b) in experiments with a mutant of the microalgae
Chlorella vulgaris Beyerinck. This mutant produced no chlorophyll but was able to
accumulate either protoporphyrin IX or Mg protoporphyrin IX. From these studies,
it was shown that heme synthesized in animal’s red blood cells followed the same
biosynthetic pathway and with the same intermediate compounds as the synthesis of
protoporphyrin IX in the chloroplast of green plants (Granick 1954). Thus, it became
apparent that protoporphyrin IX was the last common molecule in the biosynthetic
pathways for heme and chlorophyll production. The insertion of Fe yields the iron
protoporphyrin (heme) molecule, while Mg insertion yields Mg protoporphyrin, a
precursor of protochlorophyll that will lead to chlorophyll molecule (Marks 1966). It
was around 1940 (Fischer and Orth 1943) that the structure of heme was elucidated
and in 1960, the total synthesis of chlorophyll was finally published (Woodward
et al. 1960). A general and synthetic sequence of steps in chlorophyll a biosynthesis
is presented in Fig. 1.1, as modified from Bogorad (1967); the chemical structure of
heme, protoporphyrins IX, and chlorophyll a are shown in Fig. 1.2.
Chlorophyll a biosynthesis in algae is a complex process that comprises several
enzymatic reactions and stereo-specific reductions that will produce the chlorophyllide a from protochlorophyllide a. The first is converted into chlorophyll a, being the
7
f (Allakhverdiev et al. 2016). Chl f has been shown to have absorption peak at
about 706 nm and a maximum fluorescence emission at 722 nm at room temperature
in methanol, making it the most red-shifted chlorophyll discovered to date (Chen
et al. 2010). The photophysical and photochemical functions of Chl f are still poorly
known (Li et al. 2012). The photophysical and photochemical properties and function of Chl f are being now investigated (Li et al. 2012, Gan et al. 2014, Ho 2018,
Kurashov et al. 2019).
1.3 Biosynthesis of Chlorophylls: A Short Overview
The pathways of chlorophyll a biosynthesis were based in experiments with leaves
(Smith 1948), a mutant of Chlorella that accumulated protoprophyrin IX but not
chlorophyll (Granick 1948a), and additional observations with heme (Fe protoporphyrin IX) (Shemin and Wittenberg 1951). In details, the history and the pigment
biosynthesis can be found in Marks (1966) and Bogorad (1967). Hendry and Jones
(1980) present a detailed study comparing heme and chlorophylls, with the biosynthetic pathways of tetrapyrroles and their natural occurrence. A more recent text on
the biochemistry and regulation of chlorophyll biosynthesis can be found in Cahoon
and Timko (2003).
The first indication of relation between the structure of the green pigment of plants
(chlorophyll) and heme, the prosthetic group of the red blood pigment hemoglobin,
dates back to 1880, as reported in Marks (1966). In spite of the differences in these two
molecules (chlorophylls and heme), the arrangement of their side chains is identical.
Their structural similarity has generated the idea that the biosynthesis of heme and
chlorophylls could have similar pathways. This was further confirmed by Granick and
co-workers (Granick 1948a, 1948b) in experiments with a mutant of the microalgae
Chlorella vulgaris Beyerinck. This mutant produced no chlorophyll but was able to
accumulate either protoporphyrin IX or Mg protoporphyrin IX. From these studies,
it was shown that heme synthesized in animal’s red blood cells followed the same
biosynthetic pathway and with the same intermediate compounds as the synthesis of
protoporphyrin IX in the chloroplast of green plants (Granick 1954). Thus, it became
apparent that protoporphyrin IX was the last common molecule in the biosynthetic
pathways for heme and chlorophyll production. The insertion of Fe yields the iron
protoporphyrin (heme) molecule, while Mg insertion yields Mg protoporphyrin, a
precursor of protochlorophyll that will lead to chlorophyll molecule (Marks 1966). It
was around 1940 (Fischer and Orth 1943) that the structure of heme was elucidated
and in 1960, the total synthesis of chlorophyll was finally published (Woodward
et al. 1960). A general and synthetic sequence of steps in chlorophyll a biosynthesis
is presented in Fig. 1.1, as modified from Bogorad (1967); the chemical structure of
heme, protoporphyrins IX, and chlorophyll a are shown in Fig. 1.2.
Chlorophyll a biosynthesis in algae is a complex process that comprises several
enzymatic reactions and stereo-specific reductions that will produce the chlorophyllide a from protochlorophyllide a. The first is converted into chlorophyll a, being the