Figure 3.

Detection of the G41C mutation in katG DNA by structure-specific probe binding under low stringency conditions. (A) Proposed structures of the wild-type (WT) and mutant (G41C) 423 nt fragments of katG DNA. Probes 1, 1a, 2 and 3 are shown by solid lines at the regions complementary to the targets. Non-complementary nucleotides in the probes are indicated. (B) Relative binding affinities of probes 1, 1a, 2 and 3 with WT and G41C targets labeled with fluorescein at the 5′-end (5′-Fl). (C) Identical to (B) but with the targets internally labeled with fluorescein (Fl-Int). (D) Identical to (C) but with the internally labeled targets treated with AvaI (Fl-Int-Ava I). The binding affinities for WT and G41C targets are shown by white and gray rectangles, respectively. Error bars indicate the standard deviations obtained from triplicate measurements.