NUCLEOTIDE INCORPORATION OPPOSITE DEGENERATE BASES BY TAQ DNA-POLYMERASE

Oligodeoxyribonucleotides containing degenerate bases, 6H,8H-3,4-dihyd ropyrimido[4,5-c] [1,2]oxazin-7-one (P), 2-amino-6-methoxyaminopurine (K), and N-6-methoxyadenine (Z) were made on a DNA synthesizer. The ol igonucleotides were used for the preparation of DNA templates by enzym atic ligation of DNA fragments. The templates were annealed with a pri mer and extended with Tag DNA polymerase and dNTPs to reveal the nucle otide(s) incorporated opposite the modified bases. Analysis of the pro ducts showed that A was inserted opposite the pyrimidine P and T oppos ite the purines, K and Z. Incorporation of a small amount of C opposit e K was also observed.