Differential elimination of radioiodine from single- and double-stranded 125I-DNA.
[125I]Iododeoxyuridyl residues in heat-denatured I-DNA underwent deiodination in solutions of sodium bisulfite. In 0.5 M bisulfite containing 1 M trimethylamine, 92% of the iodine was released from denatured DNA in 2.5 min at 60 degrees C. By contrast iodine in native I-DNA remained stably bound under the same condition. The deiodination of [125I]I-deoxyuridine residues incorporated by enzymatic copying of oligomers 60 nucleotides in length was found to be pairing dependent. While 125I in iododeoxyuridine paired to deoxyadenosine in a complementary oligomer remained approximately equal to 90% covalently bound in the presence of 1 M bisulfite at 60 C, when the iodouridylate residue was mismatched greater than 96% was eliminated in 4 min. The presence of mismatches in the two nucleotides adjacent to a [125I]iododeoxyuridine/deoxyadenosine pair increased the elimination of iodine. The results indicate that the deiodination reaction might be applied for the rapid detection of variations in natural DNA sequences.
Scherberg
N
N
University of Chicago Hospitals and Clinics, IL 60637.
D004247:DNA; D004277:DNA, Single-Stranded; D006358:Hot Temperature; D007457:Iodine Radioisotopes; D009691:Nucleic Acid Denaturation
D004277:DNA, Single-Stranded; D007457:Iodine Radioisotopes; D004247:DNA