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  • 1
    Electronic Resource
    Electronic Resource
    Formation of pyrophosphate, tripolyphosphate, and phosphorylimidazole with the thioester, N, S-diacetylcysteamine, as the condensing agent (1981)
    Springer
    Journal of molecular evolution 18 (1981), S. 24-29 
    Details
    ISSN: 1432-1432
    Keywords: Thioester ; Pyrophosphate ; Tripolyphosphate ; Phosphorylimidazole ; Molecular evolution ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Reaction of 0.20M orthophosphate with 0.20M N,S-diacetylcysteamine in 0.40M imidazole at pH 7.0 or 8.0 under drying conditions at 50°C for 6 days yields pyrophosphate and tripolyphosphate in the presence and absence of 0.10M divalent metal ion. The efficiency of utilization of N,S-diacetylcysteamine in the formation of pyrophosphate linkages ranges from 3 – 8% under the above conditions. The thioester, N,S-diacetylcysteamine, and imidazole are required for phosphoanhydride formation. Reaction of 0.40M orthophosphate with 0.20M N, S-diacetylcysteamine in 0.40M imidazole at ambient temperature for 6 days yields phosphorylimidazole in the absence or presence of 0.05M MgCl2. Phosphorylimidazole and pyrophosphate are formed in the presence of 0.05M CaCl2; pyrophosphate and tripolyphosphate are formed with 0.15M CaCl2. The efficiency of utilization of N,S-diacetylcysteamine in the formation of pyrophosphate linkages is roughly 7% at 6 days of reaction with 0.15M CaCl2. The thioester, N,S-diacetylcysteamine and imidazole are required for the formation of phosphoanhydrides. The significance of these reactions to molecular evolution is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01733208
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  • 2
    Electronic Resource
    Electronic Resource
    Thiol-catalyzed formation of lactate and glycerate from glyceraldehyde (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 237-243 
    Details
    ISSN: 1432-1432
    Keywords: Glyceraldehyde ; Intramolecular ; Rearrangement ; Lactic Acid ; Oxidation ; Glyceric acid ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The formation of lactate from glyceraldehyde is catalyzed by the thiol, N-acetylcysteine, at ambient temperature in aqueous sodium phosphate (pH 7.0). The rate of lactate formation is more rapid at higher concentrations of sodium phosphate and is essentially the same in the presence and absence of oxygen. The formation of lactate is efficient, but proceeds slowly with an 8.8% yield of lactate after 16 days from 10 mM glyceraldehyde in the presence of 12.5 mM N-acetylcysteine and 500 mM sodium phosphate (pH 7.0). The formation of glycerate from glyceraldehyde, that occurs in the presence of oxygen and to a small extent when oxygen has been removed, is also catalyzed by the thiol, N-acetylcysteine, under the same conditions. The dramatic increase in the rate of glycerate formation that is brought about by the thiol, N-acetylcysteine, is accompanied by an equally dramatic decrease in the rates of production of glycolate and formate. Presumably, the thiol-dependent formation of lactate and glycerate occurs via their respective thioesters. The significance of these reactions to molecular evolution is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02099971
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  • 3
    Electronic Resource
    Electronic Resource
    Formation of the thioester, N-acetyl, S-lactoylcysteine, by reaction of N-acetylcysteine with pyruvaldehyde in aqueous solution (1982)
    Springer
    Journal of molecular evolution 18 (1982), S. 354-359 
    Details
    ISSN: 1432-1432
    Keywords: Thioester ; Hemithioacetal ; Intramolecular rearrangement ; Molecular Evolution ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary N-acetylcysteine reacts efficiently with pyruvaldehyde (methylglyoxal) in aqueous solution (pH 7.0) in the presence of a weak base, like imidazole or phosphate, to give the thioester, N-acetyl, S-lactoylcysteine. Reactions of 100 mM N-acetylcysteine with 14 mM, 24 mM and 41 mM pyruvaldehyde yield, respectively, 86%, 76% and 59% N-acetyl, S-lactoylcysteine based on pyruvaldehyde. The decrease in the percent yield at higher pyruvaldehyde concentrations suggests that during its formation the thioester is not only consumed by hydrolysis, but also by reaction with some substance in the pyruvaldehyde preparation. Indeed, purified N-acetyl, S-lactoylcysteine disappears much more rapidly in the presence of pyruvaldehyde than in its absence. Presumably, N-acetyl, S-lactoylcysteine synthesis occurs by rearrangement of the hemithioacetal of N-acetylcysteine and pyruvaldehyde. The significance of this pathway of thioester formation to molecular evolution is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01733903
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  • 4
    Electronic Resource
    Electronic Resource
    Nonenzymatic formation of “energy-rich” lactoyl and glyceroyl thioesters from glyceraldehyde and a thiol (1984)
    Springer
    Journal of molecular evolution 20 (1984), S. 157-166 
    Details
    ISSN: 1432-1432
    Keywords: Glyceraldehyde ; Intramolecular rearrangement ; Oxidation ; Lactoyl thioester ; Glyceroyl thioester ; Prebiotic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The “energy-rich” thioester, N-acetyl-S-lactoylcysteine, is formed under anaerobic conditions from glyceraldehyde and N-acetylcysteine at ammbient temperature in aqueous solutions of sodium phosphate (pH 7.0). The conversion of glyceraldehyde to lactoyl thioester occurs at a rate of about 0.4%/day in reactions with 10 mM glyceraldehyde, 10 mM thiol, and 500 mM sodium phosphate (pH 7.0). Thioester formation proceeds at an estimated efficiency of 76%, since a similar reaction with 12.5 mM thiol yields 50.7% lactate at 6 months from only 66.5% of the glyceraldehyde (or its isomer, dihydroxyacetone). The formation of lactoyl thioester most likely occurs by the phosphate-catalyzed dehydration of glyceraldehyde to give pyruvaldehyde, which combines with thiol to form a hemithioacetal that rearranges to the thioester. A second energyrich thioester, N-acetyl-S-glyceroylcysteine, is also produced from glyceraldehyde when these reactions are carried out in the presence of oxygen and to a limited extent in the absence of oxygen. In the presence of oxygen the formation of glyceroyl thioester continues until the thiol disappears completely by oxidation. The significance of these reactions to the energetics of the origin of life is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257376
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