As it is formed ATR. Restoration СО2 to carbohydrates

you are: As it is formed ATR

End-products of light reactions of photosynthesis are NADPH and ATR (fig. 4.14). These connections are used then accordingly as regenerative force and as an energy source for transformation СО2 into sugar. Stages of which there is this transformation, are known under the general name ' tempo reactions ' photosynthesis.

The Sequence of reactions to ways of transformation СО2 to sugar managed to be found out thanks to application of radioactive carbon, 14С. This isotope of carbon which are breaking up with emission of r-particles, it is possible to find out by means of counter Gejgera - Muller or any other detector of radioactive radiations. Entering into photosynthesizing cages radioactive СО2, and then selecting through certain time intervals various chemical fractions and measuring their radio-activity, it is possible to track a biochemical way which passes in these cages 14С. Melvin Calvin and Endrju Benson from the Californian university in Berkeley have taken advantage of this method to establish a way of fixing of carbon at monocelled green seaweed Chlorella. Photosynthesis in cages Chlorella occurred in the presence of radioactive СО2. Formed mechenye connections ekstragirovali from cages metanolom then an investigated mix divided into separate components a method of a two-dimensional chromatography on a paper. According to this method, mix division spend at first in one direction by means of one system of solvents, and then at right angle to the first direction use other system of solvents. On received hromatogrammu imposed a x-ray film. After display of this film dark stains were found out on it in all those places where there were the connections containing radioactive carbon. In such a way it was possible to find out that in the course of photosynthesis in some minutes the great number mechenyh connections is formed. However, when time which has been taken away on photosynthesis, have reduced to 0,5 with, it was possible to find out one only three-carbon fosforilirovannoe connection - 3-fosfoglitserino-vuju acid (FGK). From here the conclusion has been drawn that FGK - it is the first stable product formed from СО2 in the course of photosynthesis.

Step degradation allocated radioactive FGK gives the chance to show that the radioactive label (it designate a symbol With or 14С) is born karboksilnaja (SOON) by group FGK and that, hence, it represents the modified form initial 14СО2. It would be possible to assume that absorbed 14СО2 incorporates to any two-carbon fragment therefore it is formed FGK, but it has not proved to be true. Calvin and Benson were engaged in searches of connection which would collect after exhaustion ' a stock 14СО2 in the course of photosynthesis. They started with the assumption what to collect in these conditions should just not used ' acceptor СО2 '. Such connection has really been found (fig. 4.15 and 4.16) and has been identified as ribulozobisfosfat (RuBP) - five-carbon fosforilirovannoe the connection which is breaking up after joining СО2 on two molecules FGK. Enzyme, katalizirujushchy this reaction, ribulozobisfosfat-karboksilaza, takes in a quantitative sense the first place among the fibers containing in a green fabric.

Fosfoglitserinovaja the acid formed from СО2, yet does not reach level vosstanovlennosti carbohydrates which corresponds aldegidnoj to group (Н-С=О); it will defend from it on one step, i.e. Degree of its oxidation karboksilnoj to group (НО-С=О). Restoration to aldehyde level is carried out at the expense of regenerative force NADPH and energy ATR - two connections representing products of light reactions of photosynthesis.

This last stage of formation of sugar from СО2 through FGK can be schematically represented in a following kind:

Fosfoglitserinovyj the aldehyde representing fosforilirovannoe derivative sugar, contains only three atoms of carbon. Meanwhile in the elementary sugar which collects in plants in some significant amount, contains six atoms of carbon. That it was formed geksoza, two molecules fosfoglitserinovogo aldehyde (or any its simple derivatives) should incorporate ' a head to a head ' and the product of this joining, geksozobisfosfat, should undergo defosforilirovaniju.

After that geksoza from a cycle can go or on synthesis of sucrose and polisaharidov, or - through a respiratory way (see gl. 5) - on construction of carbon skeletons of any other organic connections of a cage. Thus, the sugar formed in the course of photosynthesis from СО2, is basic organic substance which in cages of the higher plants is a source as of energy, and building blocks necessary for a cage.