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ALA
ALA
ALA
1
8
0
DV Proto
DV Proto
DV Proto
0
4
VMP
R
DV Mg-Proto
MV Mg-Proto
DV Mg-Proto
DV Mg-Proto
2
0
1
8
DV Mpe
DV Mpe
1
DV Mpe
2
3
8
DV Pchlide
a
4VPideR
4VPideR
4VMpeR
0
MV Pchlide a
MV Pchlide
a
DV Pchlide
a
9
POR-A
3D
3
9
8
MV Mpe
M V Chlide a
M V Chlide a
MV Mpe
1
3
POR-A
MV Pchlide b
3D
DV Chlide
a
2
0
1
M V Chlide
a
E
MV Chl a
9
MV Pchlide a
MV Pchlide a
4VCR
8
4VC
R
M V Chlide a
MV Chlide b
DV Chlide
a
4
POR-A
2
POR-A
0
4
MV Chlide a
M V Chlide a
M V Chlide a
M V Chlide
b
5
4
6
1
2
8
9
0
MV Chl
b
7
MV Chl a
DV Chlide b
DV Chl a
MV Chl a
MV Chl a
MV Chl a
MV Chl a
8
6
1
0
5
2
4VChlR
MV Chl b
DV Chl b
DV Chl b
MV Chl b
MV Chl b
MV Chl b
MV Chl
b
Fig. 7.11 Biosynthetic routes 1, 0 and 8 which are responsible for the formation of DV Mpe in
Metabolism of DV Mpe in LDV-DDV-LDDV Plants Species
As was observed for Mg-Proto, the proportion of DV to MV Mg-Proto biosynthesis
depended on the greening group affiliation, plant species and pretreatment of plant
tissues. For example cucumber cotyledons a DDV-LDV-LDDV plant tissue
(Abd-El-Mageed et al.
1997
), pretreated with Dpy accumulate more DV than MV
Mpe in darkness (Belanger et al.
1982
).
The specific role of DV Mpe as a precursor of DV Pchlide
a
was demonstrated by
conversion of exogenous DV Mpe to DV Pchlide
a
in isolated etiochloroplasts of
cucumber (Tripathy and Rebeiz
1986
), a DDV-LDV-LDDV plant species. In cucumber
etioplasts, DV Mpe was converted into 83 % DV Pchlide
a
, and 17 % MV Pchlide
a
.
To our knowledge, no kinetic studies have been performed on SAMMT purified
to homogeneity, with pure DV Mpe. Since the mechanism of action of SAMMT has
been reported to vary
i.e.
ping pong (Ellsworth and Pierre
1974
), random Bi Bi
(Ebbon and Tait
1969
), or ordered Bi Bi (Hinchigeri et al.
1984
) depending on the
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