Path of Carbon in Photosynthesis III

Technical Report · Tue Jun 01 00:00:00 EDT 1948

DOI:https://doi.org/10.2172/928029· OSTI ID:928029

Benson, A A; Calvin, M

Although the overall reaction of photosynthesis can be specified with some degree of certainty (CO{sub 2} + H{sub 2}O + light {yields} sugars + possibly other reduced substances), the intermediates through which the carbon passes during the course of this reduction have, until now, been largely a matter of conjecture. The availability of isotopic carbon, that is, a method of labeling the carbon dioxide, provides the possibility of some very direct experiments designed to recognize these intermediates and, perhaps, help to understand the complex sequence and interplay of reactions which must constitute the photochemical process itself. The general design of such experiments is an obvious one, namely the exposure of the green plant to radioactive carbon dioxide and light under a variety of conditions and for continually decreasing lengths of time, followed by the identification of the compounds into which the radioactive carbon is incorporated under each condition and time period. From such data it is clear that in principle, at least, it should be possible to establish the sequence of compounds in time through which the carbon passes on its path from carbon dioxide to the final products. In the course of shortening the photosynthetic times, one times, one ultimately arrives at the condition of exposing the plants to the radioactive carbon dioxide with a zero illumination time, that is, in the dark. Actually, in the work the systematic order of events was reversed, and they have begun by studying first the dark fixation and then the shorter photosynthetic times. The results of the beginnings of this sort of a systematic investigation are given in Table I which includes three sets of experiments, namely a dark fixation experiment and two photosynthetic experiments, one of 30 seconds duration and the other of 60 seconds duration.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USAEC
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 928029
• Report Number(s): UCRL--133
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
CARBON DIOXIDE
CHEMICAL REACTION KINETICS
ILLUMINANCE
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
REACTION INTERMEDIATES
SACCHARIDES
WATER