Abstract
The exciting reports (1,2) on the unusual structure of the oligonucleotide pppAZ1p5′A2′p5′A and its biological activity as a strong inhibitor of cell free protein synthesis (3) motivated various research groups to synthesize this low-molecular-weight 01 igonucleotide and its analogues (4,5). Since the biological activity of the 2′-5′-adenylates is rapidly lost due to cleavage of the 2′-5′-internucleotidic bond by a specific phosphodiesterase working from the 2′-end and affording a 3′-hydroxyl ribo-moiety modifications at this part of the molecule may enhance the stability towards enzymatic degradation and prolong this way the biological activity.