Name: Heat Labile Exonuclease I
Brand: ArcticZymes Technologies

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Heat-Labile Exonuclease I (HL-ExoI) is a 3’ – 5’ exonuclease, specific for single stranded DNA. The enzyme is recombinantly produced in E. coli. HL-ExoI is active at 25 – 37°C and inactivated by 1 minute incubation at 80°C or 15 minutes at 60°C.

HL-ExoI is used for degradation of ssDNA such as primers and oligos. It is also ideal for treatment of sensitive samples and useful in the development of novel molecular diagnostics applications.

Key Features

3’-5’ exonuclease specific for single stranded DNA
High activity at 25 - 37°C
Easily heat-inactivated by 1 min incubation at 80°C, or 15 min at 60°C
Moderate salt tolerance

Application

Removal of primers post-PCR prior to DNA sequencing or SNP detection

Figures

Figure 1. Inactivation of HL-Exol

Comparison of inactivation proprties of HL-ExoI and a commercial E. coli ExoI (EcExoI). After incubation for 10 min the nucleases were inactivated at 60°C for 15 min. The samples were then labelled with a 20-mer FAM and incubated for 30 min before visualization on a urea-PAGE gel.

Properties

Unit Definition

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).

Source

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

Optimal Reaction Conditions

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

Specific Activity

>50 000 U/mg.

Storage Buffer

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.

Storage & Stability

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.

ArcticZymes is dedicated to the quality of our products. We manufacture all products at our ISO 13485 certified facility in Norway.

dsDNA Endonuclease 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.

ssDNA Endonuclease Activity

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.