Simultaneous peptide and oligonucleotide formation in mixtures of amino acid, nucleoside triphosphate, imidazole, and magnesium ion

Abstract

Simultaneous peptide and oligonucleotide formation was observed in reaction mixtures of amino acid, nucleoside triphosphate, imidazole, and MgCl2. At 70 degrees C in solutions that were evaporated to dryness the formation of peptide for phe and pro was greatest with CTP relative to ATP, GTP, and UTP. Lysine exhibited a preference for GTP and glycine for UTP. At ambient temperature insolution at pH 7.8, CTP was preferred by glycine, but at pH 8.7 UTP was preferred. The glycine nucleotide phosphoramidates were also detected and characterized in reactions at 40 degrees C. The glycine-reaction preference for CTP at pH 7.8 and UTP at 8.7 suggested that the basicity of the nucleoside triphosphate was involved in increasing the peptide yield. CTP near neutrality is the most basic nucleoside triphosphate and the basic anionic form UTP could facilitate peptide formation at pH 8.7. These data, together with information on the complexing of poly(C) by GTP, led to the experimentally approchable hypothesis that GTP, by forming a basic triplex between the cytosine residues adjacent to the peptidyl adenosine and aminoacyl adenosine at the termini of two proto-tRNAs, would promote peptide bond synthesis between the aminoacyl residue and peptidyl residue.

Enhancement of peptide bond formation by polyribonucleotides on clay surfaces in fluctuating environments

“…At most, there is a two-fold difference in yields and a three-fold difference in enhancement factors between Poly C and Poly G (Table 4) and between Poly A and Poly G (Table 5) which is of the same magnitude as the roughly two-fold differences in yield due to variations in nucleotide base found by Nakashima and Fox (1972), Weber et al (1977), and Mizutani and Ponnamperuma (1978). The cause of our yield differences is not known.…”

“…It is interesting to note that 10 out of the 15 results are codonic; i.e., the polynucleotide containing the base that comprises the modern biological genetic codon for an amino acid is the one that gives the highest yield of peptide from that amino acid. The least agreement comes from the work of Weber et al (1977), which involves mononucleotides reacting to form oligonucleotides simultaneously with peptide formation, so the relevance to a template phenomenon is open to question. Nakashima and Fox (1972) found uniformly codonic results at one concentration and mixed results at another.…”

Catalysis of peptide bond formation by histidyl-histidine in a fluctuating clay environment

“…Experiments to detect these other products are underway; preliminary results indicate that significant amounts of both diketopiperazines and histidyl-bound glycine are formed, but that the turnover numbers observed for the catalyst are not greatly altered. The mechanism of catalysis by histidyl-histidine can be postulated by reference to the fact that imidazole is known to participate in acyl transfer reactions in a number of cases involving amino acids (Weber and Lacey 1974;Weber et al 1977;Weber and Orgel 1978;Lohrmann and Orgel 1973 ;Ehler and Orgel 1976). The cycling reaction on the clay surface may provide activated amino acyl groups (White and Erickson 1980) which could react with the imidazole ring of a histidine residue to produce an amino acid imidazolide.…”

Amino acid activation with adenosine 5′-phosphorimidazolide

“…0022--2844/78/0011/0009/~ 01.60 Lacey, 1975;Lohrmann et al, 1975;Sawai, Lohrmann and Orgel, 1975;Weber et al, 1977). MepA was chosen as the amino acid acceptor because it is structurally related to the 3'-terminus of t-RNA.…”