Biomedical subjects

E H Edelson

Publications and source records attributed to E H Edelson.

4 recordsLinked to original sources

PubMed1981

Structural studies on HCN oligomers.

NMR spectral studies on the HCN oligomers suggest the presence of carboxamide and urea groupings. The release of CO2, H2O, HCN, CH3CN, HCONH2 and pyridine on pyrolysis is consistent with the presence of these groupings as well as carboxylic acid groups. No basic primary amine groupings could be detected with fluorescamine. Hydrazinolysis of the HCN oligomers releases 10% of the amino acids normally released by acid hydrolysis. The oligomers give a positive biuret test but this is not due to the presence of peptide bonds. There is no conclusive evidence for the presence of peptide bonds in the HCN oligomers. No diglycine was detected on partial hydrolysis of the HCN oligomers at pH 8.5 suggesting that HCN oligomers were not a source of prebiotic peptides.

Amino Acids↗

PubMed1979

Ion-exchange separation of nucleic acid constituents by high-performance liquid chromatography.

The high-performance liquid chromatographic separation of a large variety of nucleic acid constituents on a silica-based, weak-anion exchange column was accomplished. Using this technique it was possible to achieve some relatively difficult separations, such as the separation of 2'-, 3'-, and 5'-AMP, and the separation of a mixture of ribo- and deoxyribo-nucleosides and -nucleotides. A number of other separations are demonstrated by isocratic or gradient elution. These include the separation of a mixture of nucleoside monophosphates, the separation of a mixture of nucleoside mono-, di-, and triphosphates, the separation of a mixture of nucleosides and bases, and the separation of a mixture of nucleotide oligomers. These chromatographic separations were accomplished using relatively simple experimental procedures at ambient temperatures and involved relatively short analysis times. Excellent separations were obtained, in most cases, by adjustment of buffer concentration and pH, or by addition of an organic modifier. In some cases, it was necessary to use gradient elution to achieve optimum resolution.

Animals↗

PubMed1979

The effect of clays on the oligomerization of HCN.

The reaction of 0.1 M HCN and dilute solutions of diaminomaleonitrile (DAMN) at pH 8--9 and 25 degrees C in the presence of suspensions of montmorillonite (bentonite) clays were investigated. Montmorillonite clays inhibit the oligomerization of aqueous solutions of HCN. Yields of colored oligomers, ura, and DAMN, are all diminished by clays, but the rate of loss of cyanide is not significantly decreased. The inhibition of oligomer formation is due to the clay-catalyzed decomposition of DAMN. The absence of strong binding of DAMN to clays was suggested by our failure to detect DAMN when a clay that had been incubated with DAMN was washed with spermidine (6 x 10(-3) g/liter). It was established that DAMN does not simply bind to the clays by the observation that the bulk of the radioactivity was recovered from the supernatant in the reaction of 14C-DAMN with montmorillonite. The clay-catalyzed decomposition of DAMN was observed when montmorillonite from two different sources was used and with a variety of homoinic montmorillonites and bentonites. A modification of the established procedure for using the cyanide electrode for cyanide analyses was used to follow the release of HCN from DAMN. This new method can be used in both the acidic and basic pH range and it does not result in the destruction of DAMN by the reagents used for the analysis. Quantitative analyses of the reaction solution from the clay-catalyzed decomposition of DAMN revealed the formation of 1--2 equivalents of HCN per mole of DAMN. The possible significance of these clay-catalyzed reactions in chemical evolution is discussed.

Bentonite↗

PubMed1978

HCN: a plausible source of purines, pyrimidines and amino acids on the primitive earth.

Dilute (0.1 M) solutions of HCN condense to oligomers at pH 9.2. Hydrolysis of these oligomers yields 4,5-dihydroxypyrimidine, orotic acid, 5-hydroxyuracil, adenine, 4-aminoimidazole-5-carboxamide and amino acids. These results, together with the earlier data, demonstrate that the three main classes of nitrogen-containing biomolecules, purines, pyrimidines and amino acids may have originated from HCN on the primitive earth. The observation of orotic acid and 4-aminoimidazole-5-carboxyamide suggests that the contemporary biosynthetic pathways for nucleotides may have evolved from the compounds released on hydrolysis of HCN oligomers.

Amino Acids↗