STERICAL RECOGNITION BY T-4 POLYNUCLEOTIDE KINASE OF NON-NUCLEOSIDIC MOIETIES 5'-ATTACHED TO OLIGONUCLEOTIDES

The ability of T-4 polynucleotide kinase (PNK) to phosphorylate non-nu cleosidic moieties 5'-attached to oligodeoxynucleotides (ODNs) has bee n investigated. Non-nucleosidic phosphoramidite units were prepared fr om ethane-1,2-diol and propane-1,3-diol backbones. Some of them corres ponded to pure enantiomers. They were used to obtain the corresponding 5'-end modified oligothymidylates X(pdT)(10). The free primary hydrox yl of the non-nucleosidic moieties (X) of these oligomers was phosphor ylated by PNK. We report the stereoselective phosphorylation of the L form of the 5'-end attached non-nucleosidic chiral fragments; the nonc hiral moieties were completely phosphorylated. Dimers of glycerol anal ogue and thymidine 3'-phosphate were not recognized by PNK and the sho rtest modified ODN able to be phosphorylated was a trinucleotide X(pdT )(3). A modified X(pdT)(10), bearing a cyclic abasic site (X) at its 5 '-end, was prepared by chemical synthesis from 1,2-dideoxyribose phosp horamidite and was phosphorylated with a 90% yield.