What is the Difference Between Klenow and T4 DNA Polymerase?

The main difference between Klenow and T4 DNA polymerase lies in their origins and temperature requirements. Here are the key differences:

  • Origin: Klenow fragment is a large fragment of E. coli DNA polymerase 1, while T4 DNA polymerase is the DNA polymerase 1 of bacteriophage T4.
  • Temperature: Klenow fragment can be used at 25°C or room temperature, but T4 DNA polymerase must be used at 12°C due to its robust exonuclease.

Both Klenow and T4 DNA polymerase are prokaryotic polymerases with 5′→3′ polymerase and 3′→5′ exonuclease activity. They lack 5′→3′ exonuclease activity, making them suitable for many applications in molecular biology. Both enzymes require a template and a primer to catalyze the synthesis of DNA and can be heat inactivated at 75°C.

Comparative Table: Klenow vs T4 DNA Polymerase

Klenow and T4 DNA polymerases are both used in molecular biology for DNA synthesis, but they have some differences. Here is a table comparing their characteristics:

Characteristic Klenow Fragement T4 DNA Polymerase
Origin E. coli DNA Polymerase 1 Bacteriophage T4 DNA Polymerase 1
Structure Large fragment of E. coli DNA Polymerase 1 Separate enzyme
5'→3' Polymerase Activity Present Present
3'→5' Exonuclease Activity Present Present
5'→3' Exonuclease Activity Absent Absent
Optimal Temperature 37°C 37°C
Error Rate 1 x 10^-6 1 x 10^-6
Blunt Ends Yes Yes

Both Klenow and T4 DNA polymerases have 5'→3' polymerase and 3'→5' exonuclease activity, but they lack 5'→3' exonuclease activity, making them more suitable for many applications in molecular biology. They are both used in various techniques, such as DNA sequencing, nick translation, and mutagenesis.