The DNA polymerase of T7 bacteriophage has DNA polymerase and 3' -> 5' exonuclease activities, but lacks a 5' -> 3' exonuclease domain. It is thus very similar in activity to Klenow fragment and T4 DNA polymerase.
The claim to fame for T7 DNA polymerase is it's processivity. That is to say, the average length of DNA synthesized before the enzyme dissociates from the template is considerably greater than for other enzymes. Due to this talent, the principle use of T7 DNA polymerase is in DNA sequencing by the chain termination technique.
T7 DNA polymerase can be chemically-treated or genetically engineered to abolish it's 3' -> 5' exonuclease activity. These forms of the enzyme are marketed under the name Sequenase and Sequenase 2.0, and are widely used for DNA sequencing reactions.
|
