Patent ID: 7989168

Claim:
A method of performing a primer extension reaction, the method comprising, a. contacting an oligonucleotide to (i) a template nucleic acid and (ii) a thermostable nucleic acid polymerase having 3′-5′ exonuclease activity, wherein: i. the oligonucleotide comprises a modified nucleotide that is not removed by the 3′-5′ exonuclease activity, wherein the modified nucleotide comprises a 2′ moiety selected from the group consisting of: amino, OH, O-phosphate, and phosphorothioate; ii the modified nucleotide is not at the 3′ or 5′ terminal nucleotide nor at the 3′ penultimate nucleotide of the oligonucleotide; iii. the oligonucleotide has a 3′ portion and a 5′ portion, wherein the 3′ portion comprises the nucleotides in the oligonucleotide that are 3′ of the modified nucleotide and the 5′ portion comprises the nucleotides in the oligonucleotide that are 5′ of the modified nucleotide; and iv. the contacting step is performed under conditions suitable to allow the polymerase to edit the 3′ portion of the oligonucleotide in a template-specific manner if the 3′ portion of the oligonucleotide is not 100% complementary to the template nucleic acid; and b. performing a primer extension reaction by extending the oligonucleotide in a template-dependent manner.