Biology Reference
In-Depth Information
Chapter 14
Relationship of Chlorophyll Biosynthetic
Heterogeneity to the Greening Group
Affiliation of Plants
If scientific reasoning were limited to the logical processes
of arithmetic, we should not get very far in our understanding
of the physical world (Vannevar Bush).
14.1
Introduction
As we have described at great length in the first 13 chapters, biosynthetic heterogeneity
refers to the biosynthesis of a particular metabolite by an organelle, tissue or organism
via multiple biosynthetic routes (Rebeiz et al.
2003
). It has been well documented in
delta-aminolevulinic acid (ALA), chlorophyll (Chl)
a
and vitamin B
12
biosynthesis
(Arigoni
1994
; Rebeiz et al.
1994
;Scott
1994
). As described in previous chapters,
It has been demonstrated that in green plants, Chl
a
and Chl
b
are formed via parallel
biosynthetic routes, namely (a) DV Chl
a
biosynthetic routes, (b) MV routes and
(c) mixed DV-MV routes (Kolossov and Rebeiz
2010
). Intermediates of the DV
carboxylic route consist of dicarboxylic and monocarboxylic tetrapyrroles with vinyl
groups at positions 2 and 4 of the macrocycle, such as DV protoporphyrin IX (Proto),
DV Mg-Proto, DVMg-Proto monomethyl ester (Mpe), DV Pchlide
a
, and DV Chlide
a
. The MV carboxylic routes involve dicarboxylic and monocarboxylic tetrapyrroles
including, MVMg-Proto, MVMpe, MV Pchlide
a
, andMV Chlide
a
, which have one
vinyl and one ethyl group at positions 2 and 4 of the macrocycle, respectively. The
mixed DV-MV carboxylic routes involve monocarboxylic tetrapyrroles such as DV
and MV Pchlide
a
and Chlide
a
.
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