Calvin cycle: Difference between revisions
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<StructureSection load='1rcx' size='350' side='right' caption='Spinach RuBisCO 8 large and 8 small chains complex with substrate ribulose-1,5- bisphosphate, [[1rcx]]'> | <StructureSection load='1rcx' size='350' side='right' caption='Spinach RuBisCO 8 large and 8 small chains complex with substrate ribulose-1,5- bisphosphate, [[1rcx]]'> | ||
See also [https://en.wikipedia.org/wiki/Calvin_cycle]. | See also [https://en.wikipedia.org/wiki/Calvin_cycle] and [[Carbon Fixation]]. | ||
3 CO<sub>2</sub> + 6 NADPH + 6 H<sup>+</sup> + 9 ATP + 5 H<sub>2</sub>O → glyceraldehyde-3-phosphate (G3P) + 6 NADP<sup>+</sup> + 9 ADP + 8 P<sub>i</sub> (P<sub>i</sub> = inorganic phosphate) (See also [https://en.wikipedia.org/wiki/Calvin_cycle]) | 3 CO<sub>2</sub> + 6 NADPH + 6 H<sup>+</sup> + 9 ATP + 5 H<sub>2</sub>O → glyceraldehyde-3-phosphate (G3P) + 6 NADP<sup>+</sup> + 9 ADP + 8 P<sub>i</sub> (P<sub>i</sub> = inorganic phosphate) (See also [https://en.wikipedia.org/wiki/Calvin_cycle]) | ||
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These reactions do not occur in the dark or at night. There is a light-dependent regulation of the cycle enzymes, as the third step requires NADPH. There are two regulation systems at work when the cycle must be turned on or off: the [[Thioredoxin|thioredoxin]]/[[Ferredoxin|ferredoxin]] activation system, which activates some of the cycle enzymes; and the [[RuBisCO]] enzyme activation, active in the Calvin cycle, which involves its own activase. | These reactions do not occur in the dark or at night. There is a light-dependent regulation of the cycle enzymes, as the third step requires NADPH. There are two regulation systems at work when the cycle must be turned on or off: the [[Thioredoxin|thioredoxin]]/[[Ferredoxin|ferredoxin]] activation system, which activates some of the cycle enzymes; and the [[RuBisCO]] enzyme activation, active in the Calvin cycle, which involves its own activase. | ||
The thioredoxin/ferredoxin system activates the enzymes [[Glyceraldehyde-3-Phosphate Dehydrogenase|glyceraldehyde-3-phosphate dehydrogenase]], glyceraldehyde-3-P phosphatase, fructose-1,6-bisphosphatase, sedoheptulose-1,7-bisphosphatase, and ribulose-5-phosphatase kinase, which are key points of the process. This happens when light is available, as the ferredoxin protein is reduced in the [[Photosystem I]] complex of the thylakoid electron chain when electrons are circulating through it. | The thioredoxin/ferredoxin system activates the enzymes [[Glyceraldehyde-3-Phosphate Dehydrogenase|glyceraldehyde-3-phosphate dehydrogenase]], glyceraldehyde-3-P phosphatase, [[fructose-1,6-bisphosphatase]], sedoheptulose-1,7-bisphosphatase, and ribulose-5-phosphatase kinase, which are key points of the process. This happens when light is available, as the ferredoxin protein is reduced in the [[Photosystem I]] complex of the thylakoid electron chain when electrons are circulating through it. | ||
</StructureSection> | </StructureSection> | ||
== References == | == References == | ||
<references/> | <references/> | ||