THE ORIGIN OF LIFE ON EARTH AND ELSEWHERE. II

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

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

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

Chemical Evolution and the Origin of Life

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

Atom to Adam

This report talks about the molecules which constitute today's living organism

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

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

THE PATH OF CARBON IN PHOTOSYNTHESIS

Biosynthesis begins with photosynthesis. Green plants and other photosynthetic organisms use the energy of absorbed visible light to make organic compounds from inorganic compounds. These organic compounds are the starting point for all other biosynthetic pathways. The products of photosynthesis provide not only the substrate material but also chemical energy for all subsequent biosynthesis. For example, nonphotosynthetic organisms making fats from sugars would first break down the sugars to smaller organic molecules. Some of the smaller molecules might be oxidized with O{sub 2} to CO{sub 2} and water. These reactions are accompanied by a release of chemical energy because O{sub 2} and sugar have a high chemical potential energy towards conversion to CO{sub 2} and H{sub 2}O. In a biochemical system only part of this energy would be released as heat. The heat would be used to bring about the conversion of certain enzymic cofactors to their more energetic forms. These cofactors would then enter into specific enzymic reactions in such a way as to supply energy to drive reactions in the direction of fat synthesis. Fats would be formed from the small organic molecules resulting from the breakdown of sugars. Thus sugar, a photosynthetic product, can supply both the energy and the material for the biosynthesis of fats

BRANCHED ALKANES FROM BLUE-GREEN ALGAE

Branched alkanes from blue-green algae were separated on a 750 feet high resolution capillary gas chromatographic column. The mixture was found to be 90% of 1:1 ratio 7-methyl, and 8-methyl-heptadecane, and 10% of 6-methylheptadecane. An optical rotation of +2.5 {+-} 0.5 was obtained on a 5 mg of mixture