Regio- and Diastereo-Selectivity of Montmorillonite-Catalyzed Oligomerization of Racemic Adenosine 5′-Phosphorimidazolide

Abstract

Clay is a possible candidate for an effective catalyst in prebiotic chemical evolution of biomolecules. Montmorillonite was reported to effectively catalyze oligomerization of racemic adenosine 5′-phosphorimidazolide (DL-ImpA). In the oligomerization reaction, considerable amounts of cyclic dimers as well as linear dimers were produced in the oligomerization reactions. To assess the regio- and diastereo-selectivities of the oligomerization reaction, the dimer products including cyclic dimers were completely identified by means of enzymatic degradation reactions of the products.

Keywords:

• RNA
• mononucleotide
• racemate
• clay-catalyzed oligomerization
• cyclic nucleotide

We thank the Sumitomo Foundation 2003 (Japan) for financial support.

Notes

^aReactions were carried out at 25°C for 7 days. D,L-ImpA concentration was 14 mM (Each enantiomer concentration is 7 mM) in 0.2 M NaCl, 75 mM MgCl₂, and 0.1 M buffer, pH 8.0. Percentages listed are the uncorrected HPLC absorbance readings.

^aYields were estimated based on HPLC peak area of the dimer fraction after alkaline phosphatase treatment (Figure 5c).