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ISOLEUCYL-tRNA SYNTHETASE OF E. coli B. A RAPID KINETIC INVESTIGATION OF THE L-ISOLEUCINE ACTIVATING REACTION

Description: We have investigated the preequilibrium kinetics of the L-isoleucine activation reaction catalyzed by Ile-tRNA synthetase in the presence of a fluorescent reporter group, 2-p-toluidinylnaphthalene-6-sulfonate, using the stopped-flow technique. It is found that of all the reactants involved, L-isoleucine binds slowest to the enzyme, apparently in a two-step process. The kinetics of the reaction are invariant in the presence of co-reactants, whereas the kinetics for ATP are drastically changed in the presence of Mg{sup 2+} ions. The formation of enzyme bound L-isoleucyl {approx} AMP is conveniently followed at dilute concentrations. The value for the rate constant of formation was determined to be 135 sec{sup -1} and of the reverse process to be 670 sec{sup -1} at pH 8.0 25 C. These values are considerably higher than the rate constant 15 sec{sup -1} of the dissociation reaction for L-isoleucine. The value of the kinetically defined equilibrium constant between the ternary Michaelis-Menten complex and the ternary enzyme-product complex indicates that, at equilibrium, the Michaelis-Menten complex is favored. The effect of temperature has been determined, and a tentative interpretation of the thermodynamic parameters is offered. The zero standard enthalpy and positive entropy for binding of L-isoleucine is consistent with hydrophobic interactions, whereas the enzyme-ligand complexes for ATP and pyrophosphate might be stabilized by hydrogen-bonds and ion-ion interactions. The equilibrium constant of formation of the ternary enzyme-product complex from the Michaelis-Menten complex does not increase significantly with temperature. The types of kinetic pathways have been restricted to the alternative of a random mechanism or an ordered sequential mechanism in which L-iso-leucine binds first. We believe that the mechanism is random.
Date: May 1, 1972
Creator: Holler, E. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Chemical and Photochemical Reactions of Thioctic Acid and RelatedDisulfides

Description: The carbon cycle of photosynthesis is briefly reviewed in its entirety and the experiments involving it which led to the implication of disulfide rupture in photosynthesis are indicated. A review of the organic, physical and photochemistry of disulfides, with particular reference to the five-membered disulfide rings as they appear in thioctic acid, is given.
Date: June 10, 1954
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

CHEMICAL EVOLUTION

Description: How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.
Date: June 1, 1965
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Chemical Evolution and the Origin of Life

Description: The formation of more complex carbon compounds from simple ones through the action of radiation is used in an interpretation of the original formation of such compounds on earth. The relation of plants and animals and evolution of photosynthesis is discussed in the light of the participation of sulfur compounds in the metabolism of both group.
Date: March 10, 1953
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

ENERGY RECEPTION AND TRANSFER IN PHOTOSYNTHESIS

Description: The basic information about the path of carbon in photosynthesis is reviewed together with the methods that were used to discover it. This has led to the knowledge of what is required of the photochemical reaction in the form of chemical species. Attention is then directed to the structure of the photochemical apparatus itself insofar as it is viewable by electron microscopy, and some principoles of ordered structure are devised for the types of molecules to be found in the chloroplasts. From the combination of these, a structure for the grana lamella is suggested and a mode of function proposed. Experimental test for this mode of function is underway; one method is to examine photoproduced unpaired electrons. This is discussed.
Date: September 23, 1958
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

The Nurture of Creative Science and the Men who Make It

Description: This report describes the development of work that began as an investigation of photosynthesis and that continues in this direction, but which has as a new product some entirely strngly results. Photosynthesis, the process upon which all life on earth today is ultimately dependent, achieves the conversion of electromagnetic energy from the sun into chemical energy in the form of plant material by the reduction of CO{sub 2} from the atmosphere with the liberation of O{sub 2} to the atmosphere. It has been possible to describe in some detail the way in which the plant accomplishes the reduction of carbon dioxide, using radioactive carbon as a tracer. The status of the present knowledge, and how they attained it, together with some prospectus of the future and what we can look forward to, is the principal theme of this discussion.
Date: May 1, 1958
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

THE IMPURITY OF SCIENCE

Description: Science is impure in two ways. There is not a 'pure' science. By this I mean that physics impinges on astronomy, on the one hand, and chemistry on biology on the other. And not only does each support its neighbors but derives sustenance from them. The same can be said of chemistry. Biology is, perhaps, the example par excellence today of an 'impure' science. Beyond this, there is no 'pure' science itself divorced from human values. The importance of science to the humanities and the humanities to science in their complementary contribution to the variety of human life grows daily. The need for men familiar with both is imperative. We are faced today with a social decision resulting from our progress in molecular genetics at least equal to, and probably greater than, that required of us twenty years ago with the maturity of nuclear power.
Date: April 19, 1962
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

SOME PHOTOCHEMICAL AND PHOTOPHYSICAL REACTIONS OP CHLOROPHYLL ANDITS RELATIVES

Description: The solution photochemistry of chlorophyll and chlorophyll analogs is described. Many cases of electron transfer to or from the porphyrin macrocycle have been found, but in no case has any very large degree of energy storage been achieved. Because of the very rapid back-reaction for products with a {Delta}F of approximately -30 kcal, some solid state models in which such an energy storage might be achieved are described and their possible relation to the natural photosynthetic apparatus is given. We can see that while the solid state model (phthalocyanine) allows an approach from a somewhat different point of view, the net result is the same as what was sought, but so far not found, when we looked at the solution chemistry of chlorophyll (and chlorophyll model substances), namely, the transfer of an electron, or hydrogen atom, from the excited porphyrin to an electron acceptor at a high reduction level which can be used to reduce the ultimate carbon dioxide reducers, followed by the donation of an electron ultimately from water to the remaining radical ion, or lattice, which produces the net results of the transfer of the hydrogen from water to carbon dioxide.
Date: April 11, 1960
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

ABIOGENIC INFORMATION COUPLING BETWEEN NUCLEIC ACID AND PROTEIN,OR, HOW PROTEIN AND DNA WERE MARRIED

Description: There is now experimental evidence for selectivity between the amino acid and the nucleic acid base which is the beginning of the chemical translation process from one linear system to the other. The linear system of the nucleic acid is, of course, an excellent place to store the information, whereas the linear system of the polypeptide, on the other hand, is the versatile system which can perform many different types of reactions but is unable to store information reliably. The experiments the author has described here may represent the beginning of the method of coupling of those two essential qualities which are required for the generation and evolution of a living organism.
Date: December 1, 1968
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Abstract of Paper Presented at the Symposium on Metal ChelateChemistry at Brooklyn Polytechnic Institute on April 26, 1952

Description: The essential structural element which differentiates metal chelate compounds from metal coordination compounds, or metal complexes in general, is the existence of some linkage between two or more of the donor atoms in the first coordination sphere of the metal. It is the purpose of the present discussion to examine the influences that this structural factor may have upon the physical and chemical properties of chelate compounds. Examples of well known, simple coordination compounds involving a variety of donor atoms (Oxygen, nitrogen), as well as a variety of electrostatic situations are shown in the following formula. Below each one are listed a few corresponding chelate structures.
Date: April 1, 1952
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

From Microstructure to Macrostructure and Function in thePhotochemical Apparatus

Description: A discussion is presented of the macrostructure of the chloroplast insofar as it is known and knowable by means of microscopy (visible, ultraviolet and electron). This leads to a number of principles of structure to be found in the granum universally distributed throughout the plant kingdom. A chemical analysis of the constitution of these lamellar structures leads to a deduction of structural principles for such molecules as are found therein. The application of these structural principles to the visible structure of the lamella leads to a microstructure on a molecular level of these lamellae which, in turn, leads to a theory of their function.
Date: October 22, 1958
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Chemical Evolution and the Origin of Life

Description: A discussion is presented of the elements, or at least most of the elements, that are usually thought of as required and characteristic of living materials. A continuous evolutionary process is conceived, beginning with a bare earth and leading to the random formation of more or less complex molecules from simple ones, and gradually, by the processes of random variation, autocatalysis, and selection, to more complex systems and the ordered array of desoxynucleic acid molecules which are the units that carry the continuity and order of present-day living systems.
Date: August 11, 1955
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Thioctic Acid: Physics, Chemistry, and Biology

Description: This paper constitutes a review of the experimental events that led our laboratory to focus its attention on thioctic acid, a discussion of some of the purely chemical and physical properties of thioctic acid that this awakened interest prompted us to investigate, and a brief description of some of our recent biological investigations with thioctic acid.
Date: April 2, 1956
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

QUANTUM CONVERSION IN PHOTOSYNTHESIS

Description: A new suggestion is made based on model work associated with similar measurements on the biological material itself. The primary quantum conversion act is an ionization occurring in a charge transfer complex. This is what it amounts to in chemical terms. But this process cannot occur in isolated charge transfer molecules in solution because the products cannot escape from each other. The primary quantum conversion as it occurs in modern photosynthesis can only take place in a laminated structure where the electrons and holes can escape from each other by electron migration and not by atomic migrations. This is the essential feature introduced here which differs from all the previous notions of how quantum conversion occurs in chemistry or biology.
Date: January 1, 1961
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

ROUND TRIP FROM SPACE

Description: Whence came life on the surface of the earth? Whether or not a complete answer to this question may be found within the context, and content, of modern science, may be a moot question. It is our purpose to see how far we can devise an answer, and how satisfactory it may be, within that context. We trace a path from the primitive molecules of the primeval earth's atmosphere condensed from space through the random formation of more or less complex organic molecules, using the available energy sources of ultraviolet light, ionizing radiation or atmospheric electrical discharge, through the selective formation of complex organic molecules via autocatalysis, finally, to the informatiion-transmitting molecule which is capable of self-reproduction and variation. In addition, somewhere, either during the course of this Chemical Evolution, or perhaps succeeding it, a system has been evolved in which the concentration of the reaction materials was retained in a relatively small volume of space, leading to the formation of cellular structures. Man is about to send back into space some bits of the dust from whence it originally came, It is thus not only timely but more significant than ever before to ask again the question: What are the probabilities that cellular life as we know it may exist at other sites in the universe than the surface of the earth?
Date: October 29, 1958
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

THE ORIGIN OF LIFE ON EARTH AND ELSEWHERE. II

Description: The synthesis of relatively complex organic molecules by ionizing and radical mechanisms (induced by high energy radiations, ultraviolet and electric discharge) from methane, ammonia, water, and hydrogen is described, both theoretically and experimentally. It is shown that the molecules which tend to be formed under such random conditions are the very ones which today are the common building blocks in the biological reconstruction of organic material. Such molecules are the amino acids, the simple carboxylic and hydroxy acids, purines, pyrimidines, etc. The appearance of order among such random molecules is induced by two forces, namely, autocatalysis and crystallization. The latter is particularly important in the appearance of highly efficient macromolecular structures and arrangements which are so characteristic of present-day living organisms. Points of contact of these theories with experiment are indicated, and where confirmation has been obtained it is described, and the areas of ignorance, requiring further experimentation, are defined. A first step in a possible test of these prebiotic organic syntheses on other astral bodies has been made by examining the organic material found in meteorites. The nature of the structures appearing therein is indicated.
Date: October 19, 1960
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Photosynthesis (The Path of Carbon in Photosynthesis and thePrimary Quantum Conversion Act of Photosynthesis)

Description: This constitutes a review of the path of carbon in photosynthesis as it has been elaborated through the summer of 1952, with particular attention focused on those aspects of carbon metabolism and i t s variation which have led to some direct information regarding the primary quantum conversion act. An introduction to the arguments which have been adduced in support of the idea that chlorophyll i s a physical sensitizer handing i t s excitation on to thioctic acid, a compound containing a strained 1, 2 -dithiolcyclopentane ring, i s given.
Date: November 22, 1952
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

HYDROCARBONS FROM PLANTS: ANALYTICAL METHODS AND OBSERVATIONS

Description: We have suggested that certain plants rich in hydrocarbon-like materials might be cultivated for renewable photosynthetic products. Two species were selected for experimental plantations: Euphorbia lathyris, an annual from seed and Euphorbia tirucalli, a perennial from cuttings, The yield from each species is over 10 barrels of oil/acre/year without genetic or agronomic improvement. In addition to plants, there are trees, such as species of Copaifera in Brazil and other tropical areas, which produce a diesel-like oil upon tapping. Each tree produces approximately 40 liters of hydrocarbon per year, and this material can be used directly by a diesel-powered car. Further efforts to develop plants as alternate energy sources are underway, as well as a continuing search for additional plant species throughout the world which have a similar capability.
Date: May 1, 1980
Creator: Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Fixation by Microorganisms

Description: Resting cells of eleven microorganisms were exposed to radioactive carbon dioxide for 40 minutes. The radioactive compounds formed during this time were separated and identified by paper chromatography. Resting cells of Lactobacillus casei fixed no carbon dioxide and growing cells fixed carbon dioxide primarily in malic and aspartic acids. All of the radioactive compounds formed could have become radioactive by reversal of known decarboxylation reactions.
Date: July 24, 1951
Creator: Lynch, Victoria H. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department

CARBOXYLATIONS AND DECARBOXYLATIONS

Description: A brief survey of decarboxylation reactions and carboxylation reactions that are known or presumed in biological systems will be presented. While a considerable number of amino acid decarboxylations are known, their mechanisms will not be included in the present discussion but will be reserved for a later paper in the symposium. The remaining decarboxylation reactions may be subdivided into oxidative and nonoxidative decarboxylations. In most cases, these reactions are practically irreversible except when coupled with suitable energy-yielding systems. The carboxylation reactions which are useful in the formation of carbon-carbon bonds in biological systems seem to fall into two or three groups: those which exhibit an apparent ATP requirement, and those which exhibit a reduced pyridine nucleotide requirement, and those which exhibit no apparent ATP requirement. Of the first group at least four cases, and possibly six or seven, are known, and one interpretation of them involves the preliminary formation of 'active' carbon dioxide, generally in the form of a carbonic acid-phosphoric acid anhydride. Those exhibiting no apparent ATP requirement seem to be susceptible to classifications as enol carboxylations in which the energy level of the substrate compound is high, rather than that of the carbon dioxide. There appear to be at least three examples of this latter type known, amongs them being the carboxy-dismutase reaction of ribulose diphosphate with carbon dioxide.
Date: April 21, 1959
Creator: Calvin, Melvin & Pon, Ning G.
Partner: UNT Libraries Government Documents Department