Generation of long RNA chains in water.

The synthesis of RNA chains from 3',5'-cAMP and 3',5'-cGMP was observed. The RNA chains formed in water, at moderate temperatures (40-90 degrees C), in the absence of enzymes or inorganic catalysts. As determined by RNase analyses, the bonds formed were canonical 3',5'-phosphodiester bonds. The polymerizations are based on two reactions not previously described: 1) oligomerization of 3', 5'-cGMP to approximately 25-nucleotide-long RNA molecules, and of 3',5'-cAMP to 4- to 8-nucleotide-long molecules. Oligonucleotide A molecules were further extended by reciprocal terminal ligation to yield RNA molecules up to >120 nucleotides long and 2) chain extension by terminal ligation of newly polymerized products of 3',5'-cGMP on preformed oligonucleotides. The enzyme- and template-independent synthesis of long oligomers in water from prebiotically affordable precursors approaches the concept of spontaneous generation of (pre)genetic information.