Effect of Dinucleoside Pyrophosphates on the Oligomerization of Activated Mononucleotides on Na^+-MONTMORILLONITE: REACTION OF 4-(CH_3)_2NpypA WITH A^5'pA
The oligomerization of adenosine 5'-phosphoro-4-(dimethylamino)pyridinium (4-(CH_3)_2\-NpypA) and diadenosine 5',5'-pyrophosphate (A^5'ppA) (9:1) on Na^+-montmorillonite was studied. The oligomers were isolated and analyzed by selective enzymatic hydrolyses and the oligomeric composition and the percent of 3',5'-phosphodiester linkages present in each fraction was determined. The longest oligomers formed (11-mers) are slightly shorter than those produced in the absence of A^5'ppA (12-mers). Smaller amounts of A^5'ppA are incorporated into the oligomers than in the ImpA/A^5'ppA reaction. The regioselectivity of 3',5'-phosphodiester bond formation is comparable to that of the oligomerization of 4-(CH_3)_2NpypA alone. An explanation of these data is proposed and the possible effect of dinucleoside pyrophosphate on prebiotic RNA formation is discussed.