Capture in the gel: intermoleculare triplex formation during gel electrophoresis.

Analysis of unusual gel mobility patterns formed by certain DNA triplexes has revealed that intermolecular triplex formation can occur during gel electrophoresis when a faster migrating single strand overtakes a slower migrating band containing a duplex of appropriate sequence. Control experiments showed that this capture of the third strand occurs by sequence-specific hybridization rather than some nonspecific retardation. This phenomenon can be used to detect triplexes by a gel-shift assay even if their lifetime is much shorter than the time of gel electrophoresis.