The Chl a Carboxylic Biosynthetic Routes: Reactions Between Mg-Protoporphyrin IX and Protochlorophyllide a - Chlorophyll Biosynthesis and Technological Applications - page 197

Fig. 7.2 DV Mg-Proto
Mg-Proto pool of higher plants was determined by chemical derivatization coupled
to analytical fluorescence spectroscopy at 77 K (Belanger and Rebeiz 1982 ).
Biosynthetic Heterogeneity of Divinyl (DV) Mg-Proto in DDV-LDV-LDDV
Plants
The biosynthesis of DV Mg-Proto from DV Proto was first reported in isolated
cucumber etiochloroplasts in the presence of added ATP and Mg (Tripathy and
Rebeiz 1986 ). In Fig. 7.3 , the biosynthesis of DV Mg-proto from DV Proto is
depicted to occur in three different thylakoid environments as suggested by multi-
ple resonance energy transfer from Mp(e) to various Chl a -Protein complexes
(Table 6.1 , Chap. 6 ) and (Kolossov et al. 2003 ), as well as further conversions to
Pchlides and Chls as will be discussed later. It is unclear at this stage whether the
spatial biosynthetic heterogeneity of DV Mg-Proto is accompanied by chemical
biosynthetic heterogeneity or not. In other words, it is unclear whether the proposed
biosynthesis of DV Mg-Proto from DV Proto via routes 1, 0, and 8 is catalyzed by
identical Mg-Proto chelatases or by different Mg-Proto chelatase isozymes. These
biosynthetic routes will be discussed further later on.
Biosynthetic Heterogeneity of DV Mg-Proto in DMV-LDV-LDMV Plant
Species Like Barley
The accumulation of DV Mg-Proto in LDV-DDV-LDMV plant species such as
Corn and other monocots treated with ALA and ALA +Dpy has been reported
earlier (Rebeiz 1991 ). To our knowledge the direct conversion of DV Proto to DV
Mg-proto in organello or in vitro, in DMV-LDV-LDMV plants has not been
reported, and in my opinion is an oversight.
In Fig. 7.4 , the biosynthesis of DV Mg-proto from DV Proto in DMV-LDV-
LDMV plants is visualized to occur in four different thylakoid environments from
DV Proto via routes 10, 11, 0 0 and 12. This was suggested by multiple resonance
energy transfer fromMp(e) to various Chl a -Protein complexes (Table 6.1 , Chap. 6 )
(Kolossov et al., 2003 ), and by further conversions of DV Mg-Proto to Pchlides and
Chls, as will be discussed later.
It is unclear at this stage whether the spatial biosynthetic heterogeneity of DV
Mg-Proto is accompanied by chemical biosynthetic heterogeneity or not. In other