N2-SUBSTITUTED-2'-DEOXYGUANOSINE 5'-TRIPHOSPHATES AS SUBSTRATES FOR ESCHERICHIA-COLI DNA-POLYMERASE-I

Several N2-alkyl and N2-phenyl 2'-deoxyguanosine 5'-triphosphates and 2-bromo-2'-deoxyinosine 5'-triphosphate were synthesized and tested as substrates for E. coli DNA polymerase I with a template: primer system requiring incorporation of 85 nucleotides. N2-Methyl-dGTP and N2-ethyl-dGTP were found to be efficiently incorporated in place of dGTP to give full length product. N2-n-Hexyl-dGTP supported limited full length synthesis at high concentration, but N2-phenyl- and N2-(p-n-butylphenyl)-dGTP were poor substrates. 2-Bromo-2'-deoxyinosine 5'-triphosphate was a good substrate for pol I, and it was a replacement only for dGTP. Melting temperatures of oligodeoxyribonucleotides containing N2-alkyl-dG residues, annealed to complementary single stranded DNA, were lower than that of the normal oligomer.