title: Kinetics of branch migration in double-stranded DNA.
abstract: The rate of branch migration in double stranded DNA has been measured by the use of a unique substrate formed by the action of the EcoRI restriction endonuclease on the dimeric figure-8 configuration of the replicative form DNA of phage G4. The figure-8 and the X-form derived from it contain a junction of the kind postulated to occur in the Holliday structure and to be an essential feature of a number of models of recombination. In the X-form this junction can branch migrate to an irreversible terminal configuration consisting of two linear monomers. The disappearance of X-forms was measured by electron microscopy. A treatment of branch migration as a random walk process was developed to permit the determination of the rate of the intrinsic process, a step movement of the junction by a distance of one base pair. A value of about 6 kilobase pairs per sec at 37 degrees was obtained.
mesh_terms: D001435:Bacteriophages / Q000378:metabolism*; D004261:DNA Replication; D004279:DNA, Viral / Q000378:metabolism*; D007700:Kinetics; D008854:Microscopy, Electron; D008954:Models, Biological; D011995:Recombination, Genetic
chemical_list: D004279:DNA, Viral