Patent ID: 8034923

Claim:
A process comprising (i) incubating a mixture of an oligonucleotide, a terminal deoxyribonucleotide transferase in aqueous solution and one or more 2′-deoxynucleoside triphosphate analogs having the structure wherein Q is independently selected from the group consisting of O and S, but with not more than one Q being S, and B is a heterocycle selected from the group consisting of adenine, guanine, thymine, cytosine, uracil, diaminopurine, 7-deazaadenine, 7-deazaminoadenine, and 7-deazaguanine, and then (ii) treating the product of said incubation with a reagent that transforms the 3′-ONH 2 unit to give a second oligonucleotide product having a 3′-OH unit.