STUDIES ON THE BASE-PAIRING PROPERTIES OF DEOXYINOSINE BY SOLID-PHASEHYBRIDIZATION TO OLIGONUCLEOTIDES

Extensive analyses of the base-pairing properties of deoxyinosine to A , C, G and T were carried out by measuring the hybridisation of oligon ucleotides with deoxyinosine in various positions to complementary set s of oligonucleotides made as an array on the surface of a glass micro scope slide. With deoxyinosine in internal positions, results are cons istent with previous studies, showing a preferential order for pairing of I-C > I-A > I-G similar to I-T. With two adjacent deoxyinosines in the centre of the oligonucleotide, the order in duplex yield is CC > CA > AA > AC > GC > GA > CG > TA > TC > CT = AG > AT > GT > TT. With d eoxyinosine at the ends of the oligonucleotide, we find that at the 3' end there is the same order in duplex yield as for the deoxyinosine i n internal positions, though with lower discrimination between the bas es. When hybridisation is carried out in TMACI there is little base pa iring discrimination with deoxyinosine, or indeed any of the four natu ral bases at the 5' end. Changing the cation to Na+ increased discrimi nation slightly.