Patent ID: 8129115

Claim:
A method of modifying a nucleotide chain, comprising: providing an initial DNA nucleotide chain having at least two consecutive 2′-deoxyuridine 5′-monophosphate at the 3′ terminus; preparing a reaction mixture solution comprising: a buffer solution, the initial DNA nucleotide chain, terminal deoxynucleotidyl transferase, a divalent metal cation other than a cobalt ion, and a buffer component selected from the group consisting of 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid, 2 morpholinoethanesulfonic acid, and 3,3-dimethylglutaric acid; adding uracil-DNA glycosylase to the reaction mixture solution to degrade the at least two 2′-deoxyuridine 5′-monophosphate at the 3′-terminus of the nucleotide chain, thereby forming an aldehyde group capable of binding to a modifier having an —NH 2 group; and modifying directly the 3′-terminus of the nucleotide chain having the aldehyde group, with a modifier having an —NH 2 group.