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PHOTOSYNTHESIS

Description: The use of tracer carbon, as carbon-14, has made possible considerable progress in the mapping of the routes taken by the carbon atom from CO/sub 2/ into plant substances. The techniques of separation and identification that have made the progress possible lie largely in the region of chromatography and radioautography involving fractional-gamma amounts of material. Most of the earlier steps of carbon incorporation are now known. In addition, a number of the later steps on the routes to amino acids and proteins and other plant substances are now under investigation. As a result of the recognition of the earlier stages of carbon incorporation, a number of proposals have been made about the photochemical act itself. These proposals have led to the development of direct physical tests of their validity, and some results of these will be described. The remaining principal area of investigation involving the route of oxygen atoms from water to molecular oxygen is largely unexplored, but the use of new methods of analyzing for the heavy isotopes of oxygen may make possible more progress in this area. 44 references. (auth)
Date: June 1, 1958
Creator: Calvin, M.
Partner: UNT Libraries Government Documents Department

Synthetic chloroplasts

Description: The principal function of the chloroplast is to capture solar quanta and to store them in some stable form. We are in the process of trying to construct a totally synthetic system that would simulate some of the reactions of the two photosystems which occur in natural chloroplasts. Toward this end, we have demonstrated a number of the reactions required in separated systems. We have shown that it is possible to transfer electrons across an insulating membrane barrier with a surfactant photosensitizer. Others have shown, and we have confirmed, that it is possible to collect the two electrons necessary for the generation of molecular hydrogen on a heterogeneous catalyst suspended in water and similarly to collect the four holes on another heterogeneous catalyst suspended in water for the generation of molecular oxygen. A synthesis of some of these molecular catalysts for both these purposes is underway, with some partial success. When these partial reactions are assembled in a system, the resulting synthetic chloroplasts will not resemble the natural entity in detailed construction as they will contain no protein.
Date: June 1, 1980
Creator: Calvin, M.
Partner: UNT Libraries Government Documents Department

Gilbert Newton Lewis: his influence on physical-organic chemists at Berkeley

Description: A review is presented of the historical contributions of Gilbert N. Lewis to science and a discussion of the influence of Lewis on the research of the members of the physical-organic staff at Berkeley, including Melvin Calvin, during the twenties, thirties and forties. Some specific examples are discussed. Also, the effect of Lewis, his science and administrative concepts in the creation of excellence in a department of chemistry are reviewed.
Date: March 1, 1982
Creator: Calvin, M.
Partner: UNT Libraries Government Documents Department

Petroleum plantations. [Euphorbias]

Description: Photosynthesis is examined as an annually renewable resource for material and energy. The production of fermentation alcohol from sugar cane as a major source of materials for chemical feed-stocks is examined as well as the direct photosynthetic production of hydrocarbon from known plant sources. Experiments are underway to analyze the hydrocarbons from Euphorbias and other hydrocarbon containing plants with a view toward determining their various chemical components. In addition, experimental plantings of several species of Euphorbias have begun to obtain data on which species would be most successful. Using Euphorbia lathyris, there are indications that we may expect a yield of approximately ten barrels of hydrocarbon material per acre in a seven-month growing period on semiarid land.
Date: April 1, 1978
Creator: Calvin, M.
Partner: UNT Libraries Government Documents Department

Only source of energy

Description: Various plants that might play a role in the energy mix of the future are discussed and illustrated. Included among them are the Euphorbias and Guayule. (JGB)
Date: March 22, 1978
Creator: Calvin, G.J. & Calvin, M.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis VI.

Description: This paper is a compilation of the essential results of our experimental work in the determination of the path of carbon in photosynthesis. There are discussions of the dark fixation of photosynthesis and methods of separation and identification including paper chromatography and radioautography. The definition of the path of carbon in photosynthesis by the distribution of radioactivity Within the compounds is described.
Date: June 30, 1949
Creator: Calvin, M.
Partner: UNT Libraries Government Documents Department

Vectorially photoinduced electron-transfer processes across water-in-oil interfaces of microemulsions

Description: Artificial photosynthetic devices are potential fuel sources. The basic idea in the design of such devices is a photosensitized electron-transfer that yields chemical species capable of reducing and oxidizing water to hydrogen and oxygen. A fundamental difficulty in effecting this transfer is the thermodynamically favored back reactions of the intermediary redox species. An interfacial model composed of a water-in-oil microemulsion is suggested to provide the separation of these redox species, thereby preventing back-reactions. This model is designed to accomplish the photodecomposition of water in two separate water-in-oil microemulsions coupled by a redox reaction. Phase-transfer of one of the redox products from the water-in-oil interface to the continuous organic phase is the principle by which separation is achieved. The oxidation and reduction sites of the general model have been constructed. One system includes the photosensitized oxidation of a donor, EDTA, solubilized in the water pool, benzylnicotinamide acts as a primary acceptor that mediates by the phase transfer principle the reduction of a secondary acceptor, dimethylamino-azobenzene, solubilized in the continuous organic phase. In system two, involving the photosensitized reduction of methyl viologen, by tris(2,2'bipyridine)Ru(2+), thioophenol is used as the donor and its oxidation product is phase transferred to the continuous organic phase. The photoinduced processes accomplished in the two systems proceed along an uphill gradient of free energy. Two water soluble zinc-porphyrins can substitute for the Ru(2+) complex in the second system. As the two Zn-porphyrins are oppositely charged, the effect of electrostatic interactions on the quantum yields of viologen reduction could be evaluated. The results suggest that the surface charge of the wateroil interface strongly influences the efficiency of electron-transfer.
Date: July 1, 1980
Creator: Willner, I.; Otvos, J.W. & Calvin, M.
Partner: UNT Libraries Government Documents Department

MECHANISM OF CARCINOGENESIS OF THE POLYCYCLIC AROMATICHYDROCARBONS

Description: The carcinogenic activity of the benzo[a]pyrene 1, the 7,12-dimethylbenz[a]anthracene 2 and the 3-methylcholanthrene 3 is suggested to be determine by the electrophilic attack of the active oxygen, induced by the hydroxylating enzyme systems, on the most reactive substituting carbon atom(s). The cationic intermediate(s) with the charge mainly localized on a complementary, interrelated position(s) of the hydroxyl substituted position(s) reacts further with the cellular nucleophiles. The electrophilic nature of the ultimate chemical carcinogens constitutes the common distinctive feature that correlates their different structures and allows us to understand their carcinogenicity. The formation of a covalent bond with the nucleophiles of the biological macromolecules, nucleic acids and proteins, appears to be the essential requirement in the primary process of carcinogenesis.
Date: August 1, 1970
Creator: Cavalieri, E. & Calvin, M.
Partner: UNT Libraries Government Documents Department

The Metabolism of 2-Caroboxy-4-Ketopentitol Diphosphate

Description: 2-Carboxy-4-ketopentitol is converted enzymatically by a cell-free preparation from spinach leaves into a substance undergoing acid-lactone interconversion. This substance has no phosphate or letone group and is probably a dicarboxylic, six-carbon sugar acid or the saccharic or saccharinic acid type. The significance of these findings with regard to the metabolic role of 2-carboxy-4-ketopentitol diphosphate is discussed.
Date: July 15, 1958
Creator: Moses, V. & Calvin, M.
Partner: UNT Libraries Government Documents Department

OPTICAL PROPERTIES OF CHROMOPHORE-MACROMOLECULE COMPLEXES:ABSORPTION AND FLUORESCENCE OF ACEIDINE DIES BOUND TO POLYPHOSPHATES ANDDNA

Description: Dye-macromolecule complexes provide good models for the study of the effects of coupling between chromophores. In addition to modifications of the visible and UV absorption spectra of the dyes at small interchromophore distances, very efficient energy transfer has been demonstrated at longer distances. The probability of nonradiative transition increases with the number of excitation transfers so that an array of oscillators close to one another becomes nonfluorescent. The insertion of a dye molecule, acting as a trap for the excitation energy, in the highly ordered system of chromophores constituted by the purine and pyrimidine bases of native DNA has given results supporting the intercalation model of Lerman and providing an experimental approach to the problem of the path length of energy migration in the DNA molecule. The average excitation path length seems to be of the order of only ten base pairs, a result which can explain the lack of fluorescence of the DNA.
Date: August 1, 1963
Creator: Weill, G. & Calvin, M.
Partner: UNT Libraries Government Documents Department

THE LIFETIME OF BACTERIAL MESSENGER RNA

Description: Puromycin, an inhibitor of protein synthesis, appears to act as an inhibitor at additional sites during the induction of {beta}-galactosidase synthesis. No inhibition of the reactions proceeding during the first 20 seconds of induction was observed, but puromycin seems to prevent the accumulation of messenger RNA during the period between 20 seconds and the first appearance of enzyme activity after 3 minutes. When cells from a stationary culture are placed in fresh medium containing inducer for {beta}-galactosidase, growth, as represented by increase in turbidity and by total protein synthesis, starts within 30 seconds. By contrast, {beta}-galactosidase synthesis is greatly delayed compared with induction during exponential growth. Two other inducible enzymes show similar lags, but malic dehydrogenase, which requires no external inducer, shows no lag. The lags are not due to catabolite repression phenomena. They cannot be reduced by pretreatment of the culture with inducer, or by supplementing the fresh medium with amino acids or nucleotides. The lag is also demonstrated by an i{sup -} mutant constitutive for {beta}-galactosidase synthesis. An inhibitor of RNA synthesis, 6-azauracil, preferentially inhibits {beta}-galactosidase synthesis compared with growth in both inducible and constitutive strains. It is suggested that these observations, together with many reports in the literature that inducible enzyme synthesis is more sensitive than total growth to some inhibitors and adverse growth conditions, can be explained by supposing that messenger RNA for normally inducible enzymes is biologically more labile than that for normally constitutive proteins. The implications of this hypothesis for the achievement of cell differentiation by genetic regulation of enzyme synthesis are briefly discussed.
Date: December 1, 1963
Creator: Moses, V. & Calvin, M.
Partner: UNT Libraries Government Documents Department

Preparation of 1-C14-Propene-1 and the Mechanism of PermanganateOxidation of Propene

Description: 1-C{sup 14}-propene has been prepared. The migration of the double bond under a variety of experimental conditions in the preparation of propene has been investigated. The mechanism of the permanganate oxidation of the labeled propene has been examined; it has been found to proceed by several paths, the relative importance of which depends upon the experimental conditions, especially the pH.
Date: December 10, 1947
Creator: Fries, B.A. & Calvin, M.
Partner: UNT Libraries Government Documents Department

An Isotope Effect in Photosynthesis

Description: In the course of some kinetic studies on photosynthesis of barley seedlings, it has been found that plants utilize C{sup 12}O{sub 2} faster than C{sup 14}O{sub 2}. The plants were placed in a closed system containing an infra-red absorption-cell for the analysis of total CO{sub 2} and an ionization chamber for the determination of C{sup 14}O{sub 2} in the gas phase, both instruments recording continuously. Carbon dioxide, containing about 2% C{sup 14}O{sub 2}, was introduced in the dark and the specific activity at this point taken as unity. After a short dark period, the lights were turned on and photosynthesis was allowed to take place. A figure shows the result of a typical experiment. During the initial dark period the specific activity fell because of dilution by inactive respired CO{sub 2}. However, as photosynthesis proceeded, the specific activity of the residual CO{sub 2} rose until, when only 1/6 of it remained, the specific activity reached a peak some 20% higher than it had been at the start of photosynthesis. At this point the steady respiratory dilution became an appreciable fraction of the total remaining CO{sub 2}, and the specific activity dropped rapidly.
Date: November 23, 1948
Creator: Weigl, J.W. & Calvin, M.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis

Description: The dark fixation of carbon dioxide by green algae has been investigated and found to be closely related to photosynthesis fixation. By illumination in the absence of carbon dioxide followed by treatment with radioactive carbon dioxide in the dark, the amount fixed has been increased ten to twenty fold. This rate of maximum fixation approaches photosynthesis maximum rates. The majority of the radioactive products formed under these conditions have been identified and isolated and the distribution of labeled carbon determined. From these results a tentative scheme for the mechanism of photosynthesis is set forth.
Date: March 8, 1948
Creator: Calvin, M. & Benson, A.A.
Partner: UNT Libraries Government Documents Department

Path of Carbon in Photosynthesis III

Description: 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.
Date: June 1, 1948
Creator: Benson, A.A. & Calvin, M.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis IV. The Identity and Sequencefo the Intermediates in Sucrose Synthesis

Description: The synthesis of sucrose from C{sup 14}0{sub 22} by green algae has been investigated and the intermediates separated by the method of paper chromatography. It is shown that sucrose is the first free sugar appearing during photosynthesis. It is apparently formed by condensation of the glucose-I-phosphate and a fructose phosphate. A series of radioautographs of paper chromatograms of extracts from plants which have photosynthesized for different periods of time has been prepared. The results indicate that 2-phosphoglyceric acid is the first product synthesized from C0{sub 2} during photosynthesis.
Date: December 14, 1948
Creator: Calvin, M. & Benson, A.
Partner: UNT Libraries Government Documents Department

The Path of Carbon in Photosynthesis VII Respiration andPhotosynthesis

Description: The relationship of respiration to photosynthesis in barley seedling leaves and the algae, Chlorella and Scenedesmus, has been investigated using radioactive carbon dioxide and the techniques of paper chromatography and radioautography. The plants are allowed to photosynthesize normally for thirty seconds in c{sup 14}O{sub 2} after which they are allowed to respire in air or helium in the light or dark. Respiration of photosynthetic intermediates as evidenced by the appearance of labeled glutomic, isocitric, fumaric and succinic acids is slower in the light than in the dark. Labeled glycolic acid is observed in barley and algae. It disappears rapidly in the dark and is maintained and increased in quantity in the light in C0{sub 2}-free air.
Date: July 21, 1949
Creator: Benson, A.A. & Calvin, M.
Partner: UNT Libraries Government Documents Department

Behavior, a Balanced Network of Chemical Transformations(Biokinetics)

Description: While the concept of a biological system as a balanced network of chemical transformations is not a new one, experimental definition of specific systems has been lacking. This paper defines theoretically and experimentally a number of such networks and their behavior and response to some limited environmental changes.
Date: January 13, 1954
Creator: Bradley, D.F. & Calvin, M.
Partner: UNT Libraries Government Documents Department