Polynucleotides from Deoxyribonucleic Acids

Abstract

DINUCLEOTIDES are found amoung the products of deoxyribonuclease digestion of deoxyribonucleic acids. By fractionation of the digest on ion-exchange resins, Sinsheimer and Koerner¹ isolated a dinucleotide containing deoxyadenylic and deoxycytidylic acids and one containing deoxycytidylic acid only. Smith and Markham² treated the deoxyribonuclease digest with phosphomonoesterase, thus removing the terminal phosphoryl groups of the polynucleotides, and fractionated the resulting products by paper chromatography in 70 per cent isopropanol–water (v/v) in an ammonia atmosphere (solvent 1) into seven bands (numbered 1–7 in order of increasing R^F values). From these, by paper electrophoresis in ammonium formate buffer pH 3.5, they isolated six dinucleoside monophosphate diesters, A–p–C, A–p–T, G–p–T, C–p–T, C–p–C and T–p–T (where A = deoxyadenosine, G = deoxyguanosine, C = deoxycytidine, T = thymidine and p indicates a phosphoric acid residue giving two nucleosides). These originated from the corresponding dinucleotides in the deoxyribonuclease digest.