Studies on nucleic acid reassociation kinetics: reactivity of single-stranded tails in DNA-DNA renaturation.

The reassociation kinetics of Escherichia coli DNA were measured by S1 nuclease resistance and hydroxyapatite binding. While the reaction assayed by hydroxyapatite displays second order kinetics, the S1 nuclease measurements follow a non-second order from, as previously reported by Morrow (Ph.D. Dissertation, Stanford University. 1974). Much of the reaction measured with S1 nuclease occurs between single stranded regions of fragments already bearing duplex structures from previous collisions, and between such regions and totally free single strands. Experimental determinations indicate that the nucleation rate of single stranded regions on fragments also containing duplexes is inhibited by an average factor of 2 to 4.