T7 Exonuclease

Description:
T7 Exonuclease is similar to Lambda Exonuclease in that it catalyzes the stepwise hydrolysis of duplex DNA from the 5' termini liberating 5' mononucleotides. However, unlike Lambda Exonuclease, the enzyme has low processivity and it will remove both 5’-hydroxyl and 5’-phosphcryl termini. T7Exonuclease hydrolyzes duplex DNA non-processively in the 5'→3' direction from both 5'-phosphoryl or 5'-hydroxyl nucleotides by liberating oligonucleotides, as well as mononucleotides, until about 50% of the DNA is acid soluble.

Source:
Purified from an E. coli strain containing a TYB12 intein fusion.

Applications:

• Controlled stepwise digestion of double-stranded DNA from the 5' termini.
• Generating ssDNA templates for sequencing via the chain-termination method.

Unit Definition:
One unit is the amount of enzyme required to release 1 nmol of acid soluble nucleotide in
15 min at 37°C under standard assay conditions.

Recommended Storage Conditions:
 -20°C

Reference:

1. Kerr, C. and Sadowski, P. D. (1972) J. Biol. Chem. 247, 311-318.
2. Thomas, K. R. and Olivera, B. M. (1978) J. Biol. Chem. 253, 424-429.
3. Ausubel, F. M., Brent, R., Kingston, R. E., Moore, D. D., Seidman, J. G., Smith, J. A. and Struhl, K., (1987) Current Protocols in Molecular Biology (John Wiley and Sons, Inc.
4. Shon, M., Germino, J. and Bastia, D. (1982) J. Biol. Chem. 257, 13823-13827.
5. Nikiforov, T. T., Rendle, R. B., Goelet, P., Rogers, Y. H., Kotewicz,
   M. L., Anderson, S., Trainor, G. L. and Knapp, M. R. (1994) Nucl. Acids Res 22, (20), 4167-4175.
6. Kornberg, A. and Baker, T. (1991) DNA Replication, Second Edition, 591.