G6PDH have been reported, which are localized in the cyto-
sol, the plastidic stroma, and peroxisomes.
G6PDH, the rate-limiting enzyme of PPP, determines the
amount of NADPH by controlling
the metabolism of glucose
via the PPP. It is found that G6PDH played a role in against
oxidative stress in human erythrocytes that lack any other
NADPH-producing route. Recent results have demonstrated
that this enzyme also plays a protective
role against ROS in
nucleated eucaryotic cells that possess alternative routes for
the production of NADPH. Using G6PDH-deficient cell lines
it is showed that other sources of NADPH do not adequately
replace the lack of NADPH production by G6PDH. That is,
the G6PDH-deficient cells were highly sensitive to oxidative
stress compared with cells expressing
endogenous levels of
G6PDH. Furthermore, human hepatoma cells and yeast
containing high expression of G6PDH are resistant to
oxidative stress. In animal cells, G6PDH
expression is
enhanced by oxidative stress by induced drugs that either
increase the intracellular concentration of active oxygen
species (AOS) or decrease the glutathione (GSH) pool. Yu et
al. showed that G6PDH activation is inversely correlated to
GSH intracellular levels. Тhe cellular
GSH or GSSG possess
roles in the regulation of defense-related gene expression in
plant cells. The simultaneous increase in G6PDH activity
resulted from decreased GSH pool rather than AOS
production (21).
Exposure of
Plectranthus plants to 900 MHz EMF for 1
hour decreases G6PDH activity immediately
after exposure
and 2 hours later (Fig.3). It is higher at 1
st
and 24
th
hour after
the treatment.
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