An archaebacterial ATPase from Halobacterium saccharovorum.
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Ammonium Sulfate↗
Biomedical subjects
C Ponnamperuma
Publications and source records attributed to C Ponnamperuma.
Chemical evolution and the origin of life: bibliography supplement 1982.
The bibliography is the thirteenth annual supplement to the comprehensive bibliography on the same subject which was published in Space Life Sci. 2(1970), 225-295; 3(1972), 293-304; 4(1973), 309-329 and in Origins of Life 5(1974), 505-527; 6(1975), 285-300; 7(1976); 75-85; 8(1977), 59-66; 9(1978), 67-74; 10(1980), 69-87; 10(1980), 379-404; 11(1981), 273-288; 12(1982), 93-118; 13(1983), 61-80.
Earth, Planet↗
Chemical evolution and the origin of life: bibliography supplement 1981.
This bibliography is the twelfth annual supplement to the comprehensive bibliography on the same subject which was published in Space Life Sci. 2 (1970), 225-295; 3 (1972), 293-304; 4 (1973), 309-329 and in Origins of Life 5 (1974), 505-527; 6 (1975), 285-300; 7 (1976), 75-85; 8 (1977), 59-66; 9 (1978), 67-74; 10 (1980), 69-87; 10 (1980), 379-404; 11 (1981), 273-288; 12 (1982), 93-118.
Amino Acids↗
Clay and the origin of life.
Research concerning the possible role of clay in chemical evolution is reviewed. The probable importance of clays in the origin of life is assessed.
Amino Acids↗
Chemical evolution and the origin of life.
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Bibliographies as Topic↗
Amino acids from the late Precambrian Thule group, Greenland.
Amino acids were recovered at concentration level of 10-9 M/g from the interior of chert and dolomite of the Late Precambrian Thule Group. Examination of the stability of amino acids in chert under dry-heating conditions suggests that these amino acids have been preserved with a predominance of L-enantiomers in the precambrian chert. Enantiomer analysis of amino acids in dolomite showed a thermal effect resulting from a late precambrian igneous intrusion. This evidence indicates that the amino acids isolated from the Thule samples were chemical fossils and not recent contaminants.
Amino Acids↗
Effect of polynucleotides on the dimerization of glycine.
Polynucleotides were found to suppress the dimerization reaction of aqueous glycine with trimetaphosphate as the condensing agent. Small anions (chloride, acetate, and phosphate) did not show this effect. The reaction was studied at a pH of about 11.5 and at 70 degrees C and room temperature with a 13 mM concentration of glycine and trimetaphosphate. Under these conditions, the effect of the polynucleotides was in the following order: polyguanylic acid less than polycytidylic acid less than polyadenylic acid less than polyuridylic acid. The result may have a significant implication for the understanding of processes of chemical evolution.
Biological Evolution↗
Chemical evolution and the origin of life: bibliography supplement 1979.
This bibliography is the tenth annual supplement to the comprehensive bibliography on the same subject which was published in Space Life Sci. 2 (1970), 225-295; 3 (1972), 293-304; 4 (1973), 309-329 and in Origins of Life 5 (1974), 505-527; 6 (1975), 285-300; 7 (1976), 75-85; 8 (1977), 59-66; 9 (1978), 67-74; 10 (1980), 69-87; 10 (1980), 379-404.
Amino Acids↗
Gamma-irradiation of malic acid in aqueous solutions.
The gamma-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the non-volatile products. Thin layer chromatography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the gamma-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.
Aerobiosis↗
Chemical evolution and the origin of life. Bibliography Supplement 1978.
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Bibliographies as Topic↗
Purification and properties of malate dehydrogenase from the extreme thermophile Bacillus caldolyticus.
The enzyme malate dehydrogenase (EC 1.1.1.37) from an extreme thermophile B. Caldolyticus was purified to about 91% homogeneity. The molar mass of the enzyme was determined as 73 000 daltons and it is composed of two subunits, each with a molar mass of 37 000. Initial velocity studies with oxaloacetic acid and NADH as substrates at pH 8.1, over a range of temperatures, indicates that the enzyme operates via a sequential type mechanism. Van't Hoff plots of the kinetic parameters displayed sharp changes in slope at characteristic temperatures, whereas the Arrhenius plot exhibited no such breaks over the temperature interval investigated. The enzyme was found to be stable at 41 degrees C and lower temperatures. At 51 degrees C and 59 degrees C an almost immediate 20% reduction in activity was obtained, but no further inactivation occurred during the 60 min of incubation. At 59 degrees C the enzyme lost 50% of its initial activity in about 38 s. High concentration of NADH was observed to greatly stabilize the enzyme at that temperature. It is suggested that the slope changes in the Van't Hoff plots and the stability profiles at 51 degrees C and 59 degrees C are representative of a temperature induced conformational change in the enzyme.
Animals↗
The evolution of the protein synthesis system, II. From chemical evolution to biological evolution.
The sequence of events previously proposed for modern protein synthesis is reviewed. It begins with an abiological synthesis of a template, and evolves through two model autocatalytic systems to a primitive cell that has a rudimentary biological protein synthesis system. A possible scheme for the origin of tRNA's is described so as to fill the gap between the model and the modern system. Fragments of genes that existed in and around the primitive system are proposed to be precursors of tRNA's. Since these fragments must have been undesirable components for the system, the origin and evolution of tRNA's may be regarded as an excellent answer by the primitive system to adverse circumstances.
Animals↗
Chemical evolution and the origin of life: bibliography supplement 1977.
This bibliography is the eighth annual supplement to the comprehensive bibliography on the same subject which was published in Space Life Sci. 2 (1970), 225-295; 3 (1972), 293-304; 4 (1973), 309-329 and in Origins of Life 5 (1974), 505-527; 6 (1975), 285-300; 7 (1976), 75-85; 8 (1977), 59-66; 9 (1978), 67-74.
Amino Acids↗
Adsorption of protein and non-protein amino acids on a clay mineral: a possible role of selection in chemical evolution.
The adsorption of protein and non-protein amino acids by Na-montmorillonite was studied at pH 3, 7, and 10, in order to determine whether clays could have played a part in selection of protein over non-protein amino acids in prebiotic times. Five pairs of amino acids, containing two to six carbons, were used at a concentration equal to 100% cation exchange capacity of the clay in adsorption experiments. The following pairs of protein and non-protein amino acids were used: glycine and sarcosine, alpha-alanine and beta-alanine, alpha-aminobutyric acid and gamma-aminobutyric acid, valine and norvaline, L-isoleucine and D-alloisoleucine. No selective adsorption of protein amino acids occurred at varying hydrogen ion concentrations. The one difference observed in the adsorption of amino acids in the mixtures was a three- and four-fold greater adsorption of beta- and gamma-amino acids, respectively, than their alpha-amino acid counterparts under acidic and neutral conditions. Strong and weak adsorption of amino acids on the clay were correlated with mechanisms such as cation exchange and hydrogen bonding. The results of this research are significant to understanding the role of clay in chemical evolution because they do not support the role of preferential adsorption of protein over non-protein amino acids by clays.
Adsorption↗
Amino acids in a carbonaceous chondrite from Antarctica.
A carbonaceous chondrite from the Antarctic, referred to as the Allan Hills meteorite 77306, appears to be free from terrestrial organic contamination. The presence of both protein and non-protein amino acids and an equal abundance of D- and L-enantiomers of amino acids, is testimony to the extraterrestrial nature of these compounds.
Amino Acids↗
Evidence for amino acids in hydrolysates of compounds formed by ionizing radiations. I. Aqueous solutions of HCN, NH4CN, and NaCN.
Dilute, 02-free aqueous cyanides were exposed to multikilorad doses of a radioactive cobalt source. After the removal of unreacted cyanides and of volatile radiolytic products, the residue was hydrolyzed and the resulting material analyzed for amino acids. The results show the presence of five protein amino acids and five amino acids which do not occur in natural proteins. The amino acids of enantiomeric derivatives separated on an optically active column, appeared to consist of approximately equal amounts of D and L isomers. Radiation-chemical yields of amino acids were determined at various radiation doses. The results obtained support the previous findings that the free-radical initiated process is the source of oligomers which on hydrolysis release the amino acids.
Amino Acids↗
Evidence of amino acids in hydrolysates of compounds formed by ionizing radiations. II. Aqueous solutions of CH3CN and C2H5CN.
It has been shown that the action of ionizing radiations on dilute, oxygen-free, aqueous solutions of acetonitrile and propionitrile leads to the formation of oligomers, which upon hydrolyses release amino acids. The presence of nine amino acids, the same as those found in irradiated aqueous cyanides, has been established. those amino acids with asymmetric carbon atoms separated by GC method, appeared to consist of nearly equal amounts of D and L isomers. Glycine is the most abundant amino acid in hydrolysates of acetonitrile, while alanine appears in the samples of propionitrile. A comparison of all amino acids, identified in hydrolysates of various cyanides and nitriles, suggests that it is the cyano group, and a free-radical initiated mechanism, that is primarily involved in these radiation-chemical changes of potential interest to prebiotic chemistry.
Acetonitriles↗
Phosphorus, a key to life on the primitive Earth.
The phosphorus of the primitive Earth was present as phosphates. It is strongly probably that a portion of the phosphate was present as condensed phosphates. The primitive Earth was highly deficient in the total available phosphorus until a sufficient quantity of phosphorus weathered from the igneous rocks in which it was entrapped. Approximately three billion years were required for the seas to become saturated. Until this time passed the seas acted as a giant sink for phosphorus, diluting it to the extent that all forms of life were deprived of the vital nutrient. When the seas became saturated, the rate of turn over of the phosphorus increased rapidly. As the seas pulsated, they left the excess precipitate phosphorus as sedimentary rock in locally righ deposits on which life could thrive.
Apatites↗