We have completed the synthesis of such
a glyceric acid–derived oligomer containing six 5-aminouracil units (6-mer)
and have studied its base-pairing properties with DNA, RNA, and α-L-threofuranosyl-(3′ → 2′)
nucleic acid. Base pairing was strong between the 6-mer and poly-d(A) (Fig. 2),
was somewhat weaker with the corresponding poly-r(A), and even occurred with α -L-threofuranosyl-3′→ 2′)
Exploring The Chemistry Of Glyoxylate And Dihydroxyfumarate
research project such as mapping the landscape of potentially primordial informational
oligomer systems eventually demands the conception of, and the commitment to, a
detailed chemical scenario for the type of organic chemistry that is supposed to
have led to such oligomers under primordial conditions. Figure 3 depicts the chemical
nature of the scenario we have decided to study experimentally. In the reaction
cycle, glyoxylate would autocatalytically convert itself into its dimer dihydroxyfumarate.
Dihydroxyfumarate is a known compound that we postulate can act as a common starting
material for a large variety of biomolecules, such as sugars, α-amino
acids, and pyrimidines, and for other organics of etiologic interest by reactions
that are essentially unexplored thus far but are deemed compatible with the constraints
of a primordial chemistry. We are conducting exploratory studies for assessing the
chemistry of selected intermediates postulated to be formed from the chemistry of
glyoxylate and dihydroxyfumarate. Some of the promising preliminary results include
the formation of dihydroxyacetone from the reaction of dihydroxyfumarate with glyoxylate,
conversion of 2,3-dioxobutanoic acid (one of the proposed products of the reaction between glyoxylate and dihydroxyfumarate)
to alanine, and identification of hitherto undiscovered reaction pathways and intermediates
in the reaction of dihydroxyfumarate with itself and with glyoxylate.
Eschenmoser, A. On a hypothetical generational relationship between HCN and constituents of the reductive citric acid cycle. Chem. Biodivers. 4:554, 2007.
Eschenmoser, A. The search for the chemistry of life's origin. Tetrahedron 63:12821, 2007.
Koch, K., Schweizer, B., Eschenmoser, A. Reactions of the HCN-tetramer with aldehydes. Chem. Biodivers. 4:541, 2007.