Processivity

In molecular biology, processivity is a measure of the average number of nucleotides added by a DNA polymerase enzyme per association/disassociation with the template. DNA polymerases associated with DNA replication tend to be highly processive, while those associated with DNA repair tend to have low processivity. Because the binding of the polymerase to the template is the rate-limiting step in DNA synthesis, the overall rate of DNA replication during S phase of the cell cycle is dependent on the processivity of the DNA polymerases performing the replication. DNA clamp proteins are integral components of the DNA replication machinery and serve to increase the processivity of their associated polymerases. Some polymerases add over 50,000 nucleotides to a growing DNA strand before dissociating from the template strand, giving a replication rate of up to 1,000 nucleotides per second.