It is presumed that at an early stage of evolution and in the absence of a sophisticated enzyme machinery, template-directed reactions of nucleotides or nucleotide analogues may have been responsible for some “primitive” polynucleotide synthesis and information transfer. 2 Therefore a substantial effort has beendevoted to the study of these reactions under a variety of conditions, but in the absence of enzymes. Nucleotide triphosphates, abbreviated pppN (see structures), have a high energy content, but they are kinetically very stable. In the con-temporary cell this sluggishness is overcome by the action of enzymes. In the absence of enzymes the reactivity can be enhanced by using ImpN’s, an approach which has been frequently used. 3

We have studied the reactions of ImpN’s both in the presence and in the absence of an appropriate template in water. Most of the studies were focused on the reactions of guanosine'-phosphate 2-methylimidazolide, 2-MelmpG. In the presence of the templatepolycytidylate, poly (C), this monomer polymerizes quantitatively and forms oligoguanylates that are up to 40 units long. 4 In the absence of poly (C), 2-MeImpG hydrolyzes at the PN