Thermodynamics
The effects of neighboring bases and secondary structure on the frequency of frameshift mutations has been investigated in depth. Fluorescently tagged DNA, by means of base analogues, permits one to study the local changes of a DNA sequence. Studies on the effects of the length of the primer strand reveal that an equilibrium mixture of four hybridization conformations was observed when template bases looped-out as a bulge, i.e. a structure flanked on both sides by duplex DNA. In contrast, a single-loop structure with an unusual unstacked DNA conformation at its downstream edge was observed when the extruded bases were positioned at the primer–template junction, showing that misalignments can be modified by neighboring DNA secondary structure.
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