SPECULATION ON THE RNA PRECURSOR PROBLEM

While no convincing prebiotic synthesis of RNA building blocks has bee n demonstrated, at least two synthetic analogues of nucleic acids have been described whose properties are remarkably similar to those of RN A. The RNA backbone is thus not the only possible solution to the prob lem of replicating the information stored in a sequence of purines and pyrmidines. These results indirectly support the suggestion that RNA might have been preceded in evolution by a related molecule which, per haps, was more easily synthesized than RNA. New results on the prebiot ic chemistry of phosphonic acids suggest a possibility that a backbone structure based on ribose-2,4-diphosphonic acid may have formed via s ome surprisingly simple chemistry. (C) 1997 Academic Press Limited.