Carbon dioxide polysaccharides reaction

The overall chemical reaction of photosynthesis (of green plants for instance) is the combination of water and carbon dioxide to form saccharides, or polysaccharides... 

Figure 3 Biosynthetic pathways. (A) In the terpenoid coupling reaction, isomers of isopentenyl pyrophosphate are joined with the loss of pyrophosphate, leading to a linear intermediate that is cyclized to a terpenoid skeleton, as shown for the diterpene taxol. (B) In the polysaccharide coupling reaction, hexose and pentose monomers are joined with the loss of a nucleoside diphosphate, as shown for the epivancosaminyl-glucose disaccharide of vancomycin. (C) In the first step of the nonribosomal peptide coupling reaction, an aminoacyl adenylate is transferred to a carrier protein or thiolation domain (denoted T ) with loss of adenosine monophosphate. In the second step, this carrier protein-tethered aminoacyl group is coupled to the amine of an aminoacyl cosubstrate, forming a peptide bond, as shown for two residues in backbone of vancomycin. (D) In the polyketide coupling reaction, the loss of carbon dioxide from a two or three-carbon monomer yields a thioester enolate that attacks a carrier protein-tethered intermediate, forming a carbon-carbon bond as shown for the polyketone precursor of enterocin.

Bryce and Greenwood studied the kinetics of formation of the major volatile fraction from potato starch, and its components. They limited their interest to the temperature range from 156 to 337 and to the formation of water, as well as of carbon mon- and di-oxide. The results revealed the following facts. Stability toward pyrolysis within the first 20 minutes of the process falls in the order amylose < starch < amylopectin < cellulose. Autocatalysis is absent, as shown by Puddington. Both carbon mon- and di-oxide are evolved as a consequence of each of two first-order reactions. The initial one is fast, and the second is slow. The reasons are not well understood, but they probably involve some secondary physical effects. The amount of both carbon oxides is a direct function of the quantity of water produced from any polysaccharide, which, furthermore, is independent of the temperature. The activation energy for the production of carbon mon-and di-oxide reaches 161.6 kJ/mol, and is practically independent of the polysaccharide formed. At the limiting rates, the approximate ratios of water carbon dioxide carbon monoxide were found to be 16 4 1 for amylopectin, 13 3 1 for starch, 10 3 1 for amylose, and 16 5 1 for cellulose. 

Fig. 7 shows that, for starch, the production of carbon dioxide and carbon monoxide is a direct function of the water evolved. Similar behavior was found for the other polysaccharides. Furthermore, this production became independent of the temperature, the temperature at which this first occurred being dependent on the polysaccharide. Except for amylopectin, the resultant linear relation did not extrapolate to the origin, but yielded a positive quantity of water. The intercept value corresponded to 1.0-1,5% of water. This amount probably arose, not from any specific dehydration reaction, but rather from the residual, bound water. For all samples, the production of carbon dioxide and carbon monoxide at the lowest temperature was not linearly related to the yield of water. 

The isolation of chloroplasts capable of performing all of the reactions normally regarded as photosynthetic including the fixation of carbon dioxide, the evolution of oxygen and the synthesis of sugars and polysaccharides unequivocally demonstrates that the site of photosynthesis is the chloroplast. Experiments involving the fractionation of chloroplasts have further shown that the dark reactions associated with carbon dioxide fixation are located in the stroma of the chloroplast and the light reactions , electron transport and photophosphorylation, takes place in the lamellar systems. 

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