Heat Labile Exonuclease I

One unit catalyses the release of 10 nmol of acid soluble nucleotides in 30 min at 25°C. Reaction buffer: 20 mM Tris-HCl pH 7.5 at 25°C, 200 mM NaCl, 20 mM MgCl₂, 1 mM DTT, 0.01 Triton X-100, 2.5% glycerol and 3H-dATP-labelled DNA (25 ng/µl).

Recombinantly produced in an E. coli strain expressing the HL-ExoI gene originating from an Arctic marine bacterium.

0-15 mM MgCl₂ and ≤100 mM NaCl, at 25-37°C.

>50 000 U/mg.

10 mM Tris-HCl pH 7.5 (at 25°C), 200 mM NaCl, 10 mM MgCl₂, 1 mM DTT, 0.01% (v/v) Triton X-100, 50% (v/v) Glycerol.

The enzyme is stable at -20°C for 3 years in the supplied storage buffer. The enzyme tolerates at least five freeze-thaw cycles (-80°C) without loss of activity.

200 U HL-ExoI was incubated with a supercoiled plasmid (1 μg) for 4 hours at 37°C. Agarose gel electrophoresis did not reveal any transformation of closed circular DNA to nicked DNA.

100 U HL-ExoI was incubated with M13 ssDNA (0.5 μg) for 4 hours at 37°C. Agarose gel electrophoresis did not reveal any visible signs of ssDNA degradation.