Cyanamide mediated syntheses of peptides containing histidine and hydrophobic amino acids

Abstract

Using the model of a primitive earth evaporation pond, the synthesis of three histidyl peptides in yields up to 11% was demonstrated when aqueous solutions of histidine, leucine, ATP, cyanamide, and MgCl2 were evaporated and heated for 24 h at 80 degrees C. In addition, peptides were formed in yields of up to 56%, 35%, and 21%, respectively for phenylalanine, leucine, and alanine when aqueous solutions of the appropriate amino acid were evaporated and heated with cyanamide and one or more of the following components: ATP, AMP, 4-amino-5-imidazole carboxamide, or MgCl2. The greatest peptide yield occurred at pH 3. But peptide formation was demonstrated for a system of Leu, cyanamide, and MgCl2 adjusted to pH 7 with NH4OH. Peptide synthesis was also studied in the presence of CaCl2, ZnCl2, different adenosine nucleotides, and UTP to compare their effects on peptide synthesis. The optimum conditions for cyanamide mediated peptide synthesis were also studied in terms of pH, reaction time, reaction temperature, and cyanamide concentration. The major side product in nearly all reactions studied appears to be an amino acid-cyanamide adduct. Peptides were analyzed and identified by thin layer chromatography, acid hydrolysis, and enzymatic degradation.

Catalytic peptide hydrolysis by mineral surface: Implications for prebiotic chemistry

“…Clays and other fine grained sedimentary minerals may have provided the most likely surface for adsorption and condensation of amino acids owing to their high specific surface area (Ponnamperuma et al, 1982;Porter et al, 1998). Although many previous studies have examined the effects of minerals on peptide elongation in evaporative environments (Fox and Harada, 1958;Dose, 1983;Rode et al, 1999;Plankensteiner et al, 2004), as well in the presence of various condensing agents (Chang et al, 1969;Hawker and Oró , 1981;Hill et al, 1998;Liu and Orgel, 1998a,b;Leman et al, 2004), few studies have examined the catalytic effects of mineral surfaces on unactivated aqueous peptide oligomerization or degradation.…”

Copper-catalyzed amino acid condensation in water — A simple possible way of prebiotic peptide formation

“…The prebiotic formation of peptides/proteins, being very basic molecules for the evolution of living organisms, has been subject of numerous experiments and discussions, mostly based on the assumption of large amounts of condensation reagents on the primitive earth, even as cyanamides, ATP, inorganic polyphosphates and heterocyclic compounds (Hulshoff and Ponnamperuma, 1976;Hawker and Oro, 1981;Rishpon et al 1982;Rabinovitz and Hampai, 1985;Yamanaka et al, 1988). Other authors have shown that melting of amino acids within 120 and 200 °C also leads to condensation (Fox and Dose, 1977).…”

Diketopiperazine-mediated peptide formation in aqueous solution

“…However, it seems more likely to us that the chemical evolution might have taken place in the primitive oceans as a more universal place where peptides were formed from amino acids with an aid of various condensing agents and were accumulated gradually against their hydrolysis under mild conditions. Several simulation experiments were performed from such a viewpoint in aqueous solutions containing condensing agents (Steinman et al, t964, 1966;Rabinowitz et al, 1969;Chung et al, 1971;Rabinowitz and Hampei, 1978;Hawker and Oro, 1981;Sakurai and Yanagawa, 1984;Yamanaka et al, 1988).…”