The Chl a Carboxylic Biosynthetic Routes: Reactions Between Mg-Protoporphyrin IX and Protochlorophyllide a - Chlorophyll Biosynthesis and Technological Applications - page 201

Fig. 7.6 Biosynthetic route 2 which is responsible for the putative formation of MV Mg-Proto
from DV Proto in DDV-LDV-LDDV plant Species (Adapted from Fig. 6.3 of Chap. 6 and from
(Kolossov and Rebeiz 2010 )
Pchlide a (Suzuki and Bauer 1995 ). This in turn indicates that separate [4-vinyl]
reductases are active before DV Pchlide a , DV Chlide a and DV Chl a vinyl
reduction at position 4 of the macrocycle. It should be pointed that contrary to
other MV intermediates which can be formed via multiple biosynthetic routes, MV
Mg-Proto can only be formed from DV Mg-Proto via two routes namely routes
2 and 12 (Figs. 7.6 and 7.7 ).
Metabolism of MV Mg-Proto in DDV-LDV-LDDV Plant Species
The specific role of MV Mg-Proto as a precursor of MV Pchlide a was demonstrated
by conversion of exogenous MV Mg-Proto to MV Pchlide a in isolated cucumber
etiochloroplasts (Tripathy and Rebeiz 1986 ). Conversion of MV Mg-Proto to MV
Pchlide a was not accompanied by formation of DV Pchlide a . This in turn strongly
suggested that in DMV-LDV-LDDV plant species, at the level of MV Mg-Proto,
further metabolism can only proceed exclusively via MV biosynthetic routes
(Fig. 7.6 ).