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  • prebiotic peptide formation  (2)
  • Clay catalysis  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The effect of reaction conditions on montmorillonite-catalysed peptide formation (1996)
    Springer
    Catalysis letters 37 (1996), S. 267-272 
    Details
    ISSN: 1572-879X
    Keywords: catalysis ; chemical evolution ; montmorillonite ; prebiotic peptide formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oligomerization of glycine (gly) and diglycine (gly2) on montmorillonite was performed as cyclic, drying-wetting process at temperatures below 100°C, under varying reaction conditions. The influence of substrate/clay ratio, temperature and pH was found to be different for amino acid (AA) dimerization, cyclic anhydride (CA) formation and peptide chain elongation. High temperatures and neutral pH favour CA formation over diglycine production. An AA/catalyst ratio of 0.2 mmol/g leads to optimal yields. This supports the assumption that amino acid dimerization and CA formation take place at the edges of clay particles. Peptide chain elongation, starting from gly2, produces higher yields at higher temperatures and neutral pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00807765
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of smectite composition on the catalysis of peptide bond formation (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 326-333 
    Details
    ISSN: 1432-1432
    Keywords: Clay catalysis ; Glycine oligomerization ; Molecular evolution ; Prebiotic peptide formation ; Smectite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clay-catalyzed glycine and diglycine oligomerizations were performed as drying/wetting cycles at 80°C. Two trioctahedral smectites (hectorite and saponite), three pure montmorillonites, a ferruginous smectite, an Fe(II)-rich smectite, and three smectites containing goethite admixture were used as catalysts. Highest peptide bond formation was found with trioctahedral smectites. About 7% of glycine was converted to diglycine and diketopiperazine on hectorite after 7 days. In the case of dioctahedral smectites, highest yields were achieved using clays with a negative-layer charge localized in the octahedral sheets (up to 2% of converted glycine after 7 days). The presence of Fe(II) in clay is reflected in a higher efficiency in catalyzing amino acid dimerization (about 3.5% of converted glycine after 7 days). The possible significance of the results for prebiotic chemistry is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02339007
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  • 3
    Electronic Resource
    Electronic Resource
    Glycine oligomerization on silica and alumina (1997)
    Springer
    Reaction kinetics and catalysis letters 62 (1997), S. 281-286 
    Details
    ISSN: 1588-2837
    Keywords: catalysis ; silica ; alumina ; prebiotic peptide formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Oligomerization of glycine (gly) and diglycine (gly2) on silica and alumina was observed in experiments simulating wetting-drying cycles at 80°C. Glycine produces less than 1% total yield of gly2 and diketopiperazine (DKP) after one week. In experiments starting from gly2, more than 10% DKP is formed. Formation of higher oligomers (gly3–gly6) proceeded as well, with 3.8% and 5.1% total yields on silica and alumina surfaces respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02475464
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