Photosynthesis, Calvin cycle carbohydrates from

Biosynthesis of carbohydrates from carbon dioxide occurs in the stroma region of the chloroplasts via the Calvin cycle. The formation of a six-carbon sugar molecule requires six complete turns of the Calvin cycle, for each of which three ATP and two NADPH molecules are consumed. The overall biochemistry of photosynthesis for the formation of one glucose molecule from six CO2 molecules may be written as ... 

Calvin-Benson cycle The synthesis of carbohydrate from C02, in particular during oxygenic photosynthesis... 

In subaerial C3 plants substrate and reactant (s and r, respectively, in Fig. 5.56) for photosynthesis are both gaseous (atmospheric) C02, which flows through the Calvin cycle (the dark reactions of photosynthesis see Box 1.10) to yield simple carbohydrates (p), which are in turn the source of various metabolic intermediates. The source of the intracellular (kinetic) isotopic fractionation during C fixation is the enzyme rubisco (D-ribulose 1,5-diphosphate carboxylase/oxygenase). There is also an isotopic fractionation resulting from the passage of C02 into the cell. Passive diffusion of C02, at a rate , favours 12C, but the fractionation is small... 

The starting compounds for the biosynthesis of vanillic acid in genetically modified Escherichia coli are erythrose 4-phosphate and phosphoenol pyruvate. The erythrose is an intermediate product in carbohydrate metabolism (Calvin cycle, dark reaction of photosynthesis). [154, 155] Phosphoenol pyruvate is produced in several steps from 3-phosphoglyceric acid, or from a technical point of view, from succinic acid via the citric acid cycle. [156]... 

Rubisco is inhibited by 2 -carboxy-D-arabinitol-l-phosphate, which accumulates in the chloroplast in the dark [S.Gutteridge etal. (1987) in Progress in Photosynthesis Research (J. Biggins, ed.) Proc. 7th Int. Congr. Photosynth., Vol. 3, pp.395-398] and is rapidly destroyed by light. It has been called fee predawn inhibitor and insures that during the hours of darkness the Calvin cycle is switched off the latter is vital because the Calvin cycle requires ATP and this would have to come from carbohydrate oxidation in the absence of light, a process that would nullify the photosynthesis of previous day. It is believed that 2 -carboxy-D-arabinitol-l-phosphate is inhibitory because its structural similarity to 2-carboxy-3-keto-D-... 

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