Studies on nucleotides and related compounds

Abstract

The chemistry of polynucleotides is reviewed. Polydeoxyribonucleotides containing thyuddylate and deoxyadenylate residues were synthesised using aqueous solutions and either l-cyclohexyl-3 (2-morpholinoethyl) carbodiimide metho-p-toluenesulphonate (water-soluble carbodiimide) or ethoxyacetylene as a polymerising agent.
In each polymerisation, one of the mononucleotides was labelled with 32P so that nearest neighbour base-sequence analysis could be carried out on the polymeric products. The results of these analyses show that the base-sequence is essentially random, but that thymidylic acid is incorporated some 39 to 44 times more efficiently than
deoxyadenylic acid. The reasons for this predominance have been suggested.
The polydeoxyribonucleotides were also synthesised in the
presence of a primer (polyuridylic acid) under the same conditions as those employed for the above-mentioned syntheses. The results showed a significant increase in the total amount of polymer and in the relative incorporation of deoxyadenylic acid into the polymer;
the latter increasing by a factor of 8 to 9.
On the basis of these findings it is therefore, suggested
that in the absence of primer, the copolymerisation of a mixture of nucleotides is controlled by kinetic factors whereas. in the presence of a suitable primer. the base-pairing due to hydrogen hooding can.