Abstract
We briefly review the
metabolism of the chloroplast stroma, and describe the structural
modelling technique of elementary modes analysis. The technique is
applied to a model of chloroplast metabolism to investigate viable
pathways in the light, in the dark, and in the dark with the addition of
sedoheptulose-1,7-bisphosphatase (normally inactive in the dark). The results of the
analysis show that it is possible for starch degradation to enhance
photosynthetic triose phosphate export in the light, but the reactions of the
Calvin cycle alone are not capable of providing a sustainable flux
from starch to triose phosphate in the dark. When reactions of the
oxidative pentose phosphate pathway are taken into consideration, triose
phosphate export in the dark becomes possible by the operation of a
cyclic pathway not previously described. The effect of introducing
sedoheptulose-1,7-bisphosphatase to the system are relatively minor and, we
predict, innocuous in vivo. We conclude that, in contrast with the
traditional view of the Calvin cycle and oxidative pentose phosphate
pathway as separate systems, they are in fact, in the context of the
chloroplast, complementary and overlapping components of the same system.
Users
Please
log in to take part in the discussion (add own reviews or comments).