T4 DNA Polymerase has both a DNA-dependent DNA polymerase activity and
a potent 3´→5´ exonuclease activity. These characteristics
make the enzyme useful for several molecular biology applications.
Unit Definition: One unit of T4 DNA Polymerase converts 10 nmol
of dNTPs into acid-insoluble material in 30 minutes at 37°C under standard
Storage Buffer: 50% glycerol containing 50 mM Tris-HCl (pH 7.5),
0.1 M NaCl, 0.1 mM EDTA, 1 mM DTT, and 0.1% Triton® X-100.
T4 DNA Polymerase 10X Reaction Buffer: 330 mM Tris-acetate (pH 7.5),
660 mM potassium acetate, 100 mM magnesium acetate, and 5 mM DTT. dNTPs
are not included in the 10X Reaction Buffer but are available separately.
Quality Control: T4 DNA Polymerase is tested for DNA synthesis and
is free of detectable endonuclease and RNase activities.
Figure 1. Exonuclease and polymerase fill-in activities of T4 DNA Polymerase. Hind
III-digested lambda DNA was incubated with T4 DNA Polymerase in the absence
of dNTPs for the indicated time (min) at 37°C (lanes labeled with minus
sign). Note the progressive decrease in fragment size with increasing incubation
time. After exonucleolytic treatment for different time periods, aliquots
of each reaction were taken and dNTPs were added to 200 µM each. The
reactions were then continued for 10 minutes to allow the polymerase fill-in
reaction to occur, thus regenerating the original DNA fragments (lanes labeled
with plus sign).