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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 6 (1975), S. 253-270 
    ISSN: 1432-1432
    Keywords: Chemical Evolution ; Humic Acids ; Kerogen ; Melanoidins ; Sediments ; Amino Acids ; Carbohydrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary One of the major diagenetic pathways of organic matter in recent sediments involves the condensation of cellular constituents, particularly amino acids and sugars, into insoluble melanoidin-type polymers. These polymers consist mainly of humic and fulvic acids and make up the major part of the organic carbon reservoir in recent sediments. We suggest that a similar set of reactions between abiotically formed amino acids and sugars, and more generally between aldehydes and amines, occurred on a large scale in the prebiotic hydrosphere. The rapid formation of this insoluble polymeric material would have removed the bulk of the dissolved organic carbon from the primitive oceans and would thus have prevented the formation of an "organic soup". Melanoidin polymers have several properties which make them attractive hypothetical precursors of contemporary oxidation-reduction coenzymes: 1. they contain heterocyclic nitrogen compounds similar to the nitrogenous bases; 2. they contain a high concentration of stable free radicals; and 3. they tend to concentrate those heavy metals which play prominent roles in contemporary enzymic redox processes. The prebiotic formation of similar polymers could, therefore, have provided the starting point for a basic class of biochemical reactions. We suggest that the prebiotic scenario involved chemical and protoenzymic reactions at the sediment-ocean interface in relatively shallow waters and under conditions not much different from those of the recent environment.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 1 (1971), S. 112-114 
    ISSN: 1432-1432
    Keywords: Nucleotides ; Imidazole ; Condensation ; Evolution ; Prebiotic ; Oligonucleotides ; Phosphodiester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The condensation of thymidine-5′-monophosphate was carried out in the presence of imidazole in aqueous solutions at neutral pH. Formation of oligo-deoxyribonucleotides up to four units was observed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 18 (1982), S. 149-149 
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 18 (1982), S. 196-202 
    ISSN: 1432-1432
    Keywords: Prebiotic synthesis ; Phospholipids ; Phosphatidylcholine ; Cyanamide ; Liposomes ; Primitive membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using a primitive Earth evaporating pond model, the synthesis of phosphatidylcholine was accomplished when a reaction mixture of choline chloride and disodium phosphatidate, in the presence of cyanamide and traccs of acid, was evaporated and heated at temperatures ranging from 25° to 100°C for 7 hours. Optimum yields of about 15% were obtained at 80°C. Phosphatidylcholine was identified by chromatographic, chemical and enzymatic degradation methods. On enzymatic hydrolysis with phospholipase A2 and phospholipase C, lysophosphatidylcholine and phosphorylcholine were formed, respectively. Alkaline hydrolysis gave glycerophosphorylcholine. The synthesis of phosphatidylcholine as the major compound was accompanied by the formation of lysophosphatidylcholine in smaller amounts. Cyanamide was found to be essential for the formation of phosphatidylcholine, and only traces of HCl, of the order of that required to convert the disodium phosphatidate to free phosphatidic acid were found necessary for the synthesis. This work suggests that phosphatidylcholine, which is an essential component of most biological membranes, could have been synthesized on the primitive Earth.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 31 (1990), S. 167-174 
    ISSN: 1432-1432
    Keywords: Prebiotic His synthesis ; Erythrose ; Imidazole-4-acetaldehyde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The prebiotic formation of histidine (His) has been accomplished experimentally by the reacton of erythrose with formamidine followed by a Strecker synthesis. In the first step of this reaction sequence, the formation of imidazole-4-acetaldehyde took place by the condensation of erythrose and formamidine, two compounds that are known to be formed under prebiotic conditions. In a second step, the imidazole-4-acetaldehyde was converted to His, without isolation of the reaction products by adding HCN and ammonia to the reaction mixture. LC, HPLC, thermospray liquid chromatography-mass spectrometry, and tandem mass spectrometry were used to identify the product, which was obtained in a yield of 3.5% based on the ratio of His/erythrose. This is a new chemical synthesis of one of the basic amino acids which has not been synthesized prebiotically until now.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 31 (1990), S. 175-179 
    ISSN: 1432-1432
    Keywords: Histidyl-histidine synthesis ; Prebiotic catalysis ; Protoenzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Histidyl-histidine (His-His) has been synthesized in a yield of up to 14.4% under plausible prebiotic conditions using histidine (His), cyanamide, and 4-amino-5-imidazole carboxamide. A trace amount of His trimer was also detected. Because the imidazole group of His is involved in a number of important enzymatic reactions, and His-His has been shown to catalyze the prebiotic synthesis of glycyl-glycine, we expect this work will stimulate further studies on the catalytic activities of simple His-containing peptides in prebiotic reactions.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 12 (1979), S. 365-367 
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 3 (1974), S. 79-88 
    ISSN: 1432-1432
    Keywords: Polymetaphosphate Ester ; Polypeptide ; Peptide ; Diketopiperazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Following the procedure of Schramm for the synthesis of polynucleotides and polysaccharides, homopolymers ofdl-leucine,dl-phenylalanine,dl-serine, anddl-valine have been prepared in yields of 13 to 57 % through the mediation of a polymetaphosphate ester. Copolymers of the amino acids also have been prepared in lower yields (4–5 %). Infrared spectra show that the polymers are not diketopiperazines and that the polymers ofdl-leucine,dl-phenylalanine, anddl-valine are polypeptides. Conversions of as much as 57% and degrees of polymerization of approximately 12 were obtained for polyleucine. Small peptides containing possibly 2 to 3 leucine residues were detected and isolated as possible intermediates in the leucine polymerization reaction. For the polymerization ofdl-valine, a temperature of 60°C, a reaction time of 10–24 h, and a ratio of polymetaphosphate ester to amino acid of 3:1 appeared to give the best results. The Schramm procedure was initially suggested as a chemical evolution model for the formation of biological polymers under prebiotic conditions. Although the significance of this reaction to prebiological organic chemistry may be questioned, it still offers a mechanistic model for the study of the synthetic reactions involving polyphosphates which are indirectly relevant to abiotic molecular evolution and the problem of the origin of life.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 15 (1980), S. 317-331 
    ISSN: 1432-1432
    Keywords: Montmorillonite ; Kaolinite ; Prebiological synthesis ; Oligomerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this review an attempt is made to highlight the structures and properties of clay that may contribute to a better understanding of the role of clays in chemical evolution. The adsorption of organic molecules on clays has been demonstrated, as has the synthesis of bioorganic monomers in the presence of clays. For instance, amino acids (glycine, aspartic acid, threonine, alanine and others) as well as purines and pyrimidines, have been obtained from CO and NH3 in the presence of clays at relatively high temperatures (250-325°C). Carbohydrates are also easily derived from formaldehyde at relatively low temperatures (≅80°C). The oligomerization of biochemical monomers, mediated by clays has also been shown to result in the formation of polymer molecules basic to life. For instance the condensation of amino acyl adenylates at room temperature in the presence of montmorillonite is known to yield polypeptides in discrete ranges of molecular weights with degrees of polymerization up to 56. Clays have also been found to affect the condensation of mononucleotides to oligonucleotides. Although the role of clays in the origin of metabolic pathways has not been demonstrated, it is possible that clays may have played a cooperative role with catalytic peptides in an intermediate stage of prebiological chemistry preceding the emergence of life on this planet.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 1 (1972), S. 326-333 
    ISSN: 1432-1432
    Keywords: Decarboxylation ; Aspartic Acid ; B6 ; Non-enzymic ; Al3+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Non-enzymicβ-decarboxylation of aspartic acid at 85° is catalyzed by Al3+ and pyridoxal. The reaction is optimum at pH 4.0. Both Al3+ and pyridoxal are specifically required because replacing these by other cations or by other vitamin B6 derivatives greatly lowers the formation of alanine. Conversion of 8 µmoles of aspartic acid to alanine is optimum in presence of 1µmole of Al3+ and 5 µmoles of pyridoxal. Increasing the concentration of pyridoxal to more than 5 µmoles lowers the alanine formation by the latter being converted to pyruvate by transamination with the excess pyridoxal. Studies on the mechanism of decarboxylation suggest that aspartic acid is first converted to oxalacetic acid by transamination with pyridoxal which in turn is converted to pyridoxamine. This is followed by decarboxylation of oxalacetic acid to form pyruvic acid which transaminates with pyridoxamine to form alanine. The results are interpreted to suggest that the non-enzymic aspartateβ-decarboxylation process is closely related to and inseparable from the non-enzymic transamination process in a manner analogous to that reported for the highly purified asparateβ-decarboxylase. The possible significance of these results to prebiotic molecular evolution is briefly discussed.
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