Calvin photosynthesis

G. Petterson and U. Ryde Petterson, A mathematical model of the Calvin photosynthesis cycle. 

U. Ryde Petterson, Identification of possible two reactant sources of oscillations in the Calvin photosynthesis cycle and ancillary pathways. Eur. J. Biochem. 198, 613 619 (1991). 

M. Calvin, Photosynthesis as a resource for energy material , Ante. Scientist, 64, 1976, 270. 

Milstein, J., Estimation of the dynamical parameters of the Calvin photosynthesis cycle, optimization and iU conditioned inverse problems, Ph.D. Thesis, University of California, Berkeley (1975)... 

M. Calvin and J. A. Bassham, The Photosynthesis of Carbon Compounds, Benjamin, New York, 1962. 

All the O atoms evolved as Og come from water none comes from carbon dioxide. But 12 O atoms are evolved as 6 Og, and only 6 O atoms appear as 6 HgO in the equation. Also, 6 COg have 12 O atoms, yet there are only 6 O atoms in CgHigOg. How can yon account for these discrepancies Hint Consider the partial reactions of photosynthesis ATP synthesis, NADP reduction, photolysis of water, and the overall reaction for hexose synthesis in the Calvin-Benson cycle.)... 

M. Calvin, The path of carbon in photosynthesis, Nobel Lectures in Chemistry 1942 - 62, Elsevier, Amsterdam, 1964, 618-44. 

One of the first chemical applications of radioactive tracers was a set of elegant experiments on photosynthesis performed in the 1950s by Melvin Calvin. His goal was to determine the set of reactions used by plants to transform atmospheric CO2 into carbohydrates. Calvin supplied growing plant cells with CO2 enriched with 14... 

Photosynthesis in green plants occurs in two basic processes. In the dark (the Calvin cycle) carbon dioxide is reduced by a strong reducing agent, the reduced form of nicotinamide adeninedinucleotide phosphate, NADPH2, with the help of energy obtained from the conversion of ATP to ADP ... 

Fig. 6.3 The Calvin cycle or the dark reactions of photosynthesis see Cooper and also Stryer in Further Reading.

Much interest has recently been shown in artificial photosynthesis. Photosynthesis is a system for conversion or accumulation of energy. It is also interesting that some reactions occur simultaneously and continuously. Fujishima et al. [338] pointed out that a photocatalytic system resembles the process of photosynthesis in green plants. They described that there are three important parts of the overall process of photosynthesis (1) oxygen generation by the photolysis of water, (2) photophosphorylation, which accumulates energy, and (3) the Calvin cycle, which takes in and reduces carbon dioxide. The two reactions, reduction of C02 and generation of 02 from water, can occur simultaneously and continuously by a sonophotocatalytic reaction. 

The conversions conducted in both steps are currently based on empirical relationships that are more or less robust. For example, the relationship between the chlorophyll and carbon content in an average phytoplankton cell is dependent on factors that influence cell metabolism, including nutrient arailability, temperature, and light. The temperature dependence of photosynthesis is associated with an enzyme-mediated step in the Calvin cycle (Figure 7.6a). 

On p. 407, the initial step of the dark reactions in plant photosynthesis (in the Calvin cycle) is shown at the top left. 

The dark reaction of photosynthesis (Figure 2.3) is so-called as it does not require light to proceed. It does, however, require the products of the light reaction to operate and it will not, therefore, take place in the absence of light. It was discovered by Calvin and is often known as the Calvin cycle. 

Figure 2.3 The dark reaction (the Calvin cycle) of photosynthesis...

NADPH and ATP are produced in the light-dependent reactions of photosynthesis in about the same ratio (2 3) as they are consumed in the Calvin cycle. Nine ATP molecules are converted to ADP and phosphate in the generation of a molecule of triose phosphate eight of the phosphates are released as Pj and combined with eight ADP to regenerate ATP. The ninth phosphate is incorporated into the triose phosphate itself. To convert the ninth ADP to ATP, a molecule of Pj must be imported from the cytosol, as we shall see. 

Photosynthesis in vascular plants takes place in chloroplasts. In the C02-assimilating reactions (the Calvin cycle), ATP and NADPH are used to reduce C02 to triose phosphates. These reactions occur in three stages the fixation reaction itself, catalyzed by rubisco reduction of the resulting 3-phosphoglycerate to glyceraldehyde 3-phosphate and regeneration of ribulose 1,5-bisphosphate from triose phosphates. 

Identification of Key Intermediates in C02 Assimilation Calvin and his colleagues used the unicellular green alga Chlorella to study the carbon-assimilation reactions of photosynthesis. They incubated 14C02 with illuminated suspensions of algae and followed the time course of appearance... 

Melvin Calvin Chemistry Photosynthesis using 14C02... 

The chemical nature of photosynthesis had intrigued chemists for decades but little was learned about the details until radioactive 14C became available. Discovered in 1940 by Ruben and Kamen, the isotope was available in quantity by 1946 as a product of nuclear reactors. Initial studies of photosynthesis had been conducted by Ruben and Kamen using nC but 14C made rapid progress possible. In 1946 Melvin Calvin and Andrew A. Benson began their studies that elucidated the mechanism of incorporation of C02 into organic materials. 

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