Product Class: Nuclease

Nuclease BAL-31

unique buffer 30 degrees heat inactivation
Catalog #SizeConcentration
M0213S50 units1,000 units/ml
M0213L250 units1,000 units/ml



Progressive shortening of duplex DNA
Inactivation by treatment with EGTA
Supplied with 2X Reaction Buffer

Nuclease BAL-31 exonuclease degrades both 3' and 5' termini of duplex DNA without generating internal scissions. The enzyme is also a highly specific single-stranded endonuclease which cleaves at nicks, gaps and single-stranded regions of duplex DNA and RNA (1,2).
Ligation of Nuclease BAL-31 treated fragments 
Ligation of Nuclease BAL-31 treated fragments
A) Gel electrophoresis of Lambda DNA-HaeIII digest.  
B) Lambda DNA-HaeIII digest after 2 minute incubation with one unit of Nuclease BAL-31. 
C) As in (B) followed by incubation with T4 DNA Ligase.

Product Source

Purified from the culture medium of Alteromonas espejiana BAL-31. Contains a mixture of "fast" and "slow" species of the enzyme (3).

Reagents Supplied

The following reagents are supplied with this product:

Store at (°C)Concentration
Nuclease BAL-31 Reaction Buffer-202X

Advantages and Features


  • Progressive shortening of double-stranded DNA fragments at both termini (4)
  • Restriction site mapping (2)

Properties and Usage

Unit Definition

One unit is defined as the amount of enzyme required to remove 200 base pairs from each end of linearized double-stranded ΦX174 DNA (40 µg/ml) in a total reaction volume of 50 μl in 10 minutes at 30°C in 1X Nuclease BAL-31 Reaction Buffer.

Reaction Conditions

1X Nuclease BAL-31 Reaction Buffer
Incubate at 30°C

1X Nuclease BAL-31 Reaction Buffer:
20 mM Tris-HCl
600 mM NaCl
12 mM MgCl2
12 mM CaCl2
pH 8 @ 25°C

Storage Temperature


Storage Conditions

0.25 mM EDTA
10 mM Tris-HCl
50 mM NaCl
1.5 mM CaCl2
1.5 mM MgCl2
200 μg/ml BSA
50% Glycerol
pH 8.0 @ 25°C

Heat Inactivation

65°C for 10 min

Heat Inactivated


Quality Control

Quality Assurance Statement

  • Purified free of detectable double-stranded endonuclease activity.

Supporting Documents

The following is a list of Safety Data Sheet (SDS) that apply to this product to help you use it safely.
The Product Summary Sheet, or Data Card, includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name the majority of these document files: [Catalog Number]Datasheet-Lot[Lot Number]. For those product lots not listed below, please contact NEB at or fill out the Technical Support Form for appropriate document.


  1. Duplex products of the exonuclease are a mixture of blunt and staggered ends. This mixture can be cloned directly, although maximal ligation efficiency requires repairing the staggered ends with a suitable DNA polymerase.
  2. If necessary, the enzyme may be diluted in reaction buffer prior to use.
  3. Activity is linear with enzyme concentration.
  4. Heat Inactivation will only work in the presence of 20mM EGTA.


  1. Gray, H.B. et al. (1975). Nucl. Acids Res.. 2, 1459-1492.
  2. Legerski, R.J. et al. (1978). Nucl. Acids Res.. 5, 1445-1463.
  3. Wei, C.-F. et al. (1983). J. Biol. Chem.. 258, 13506-13512.
  4. Sambrook, J., Fritsch, E.F. and Maniatis, T. (1989). Molecular Cloning: A Laboratory Manual (2nd Ed.). 5.73-5.75.
  1. Can Nuclease BAL-31 be used to remove 10 base pairs from the end of a DNA fragment?
  2. Why does all of the DNA get degraded when I use Nuclease BAL-31?
  3. Can Nuclease BAL-31 be heat inactivated?
  4. Is Nuclease BAL-31 active in other NEBuffers?
  5. Can Nuclease BAL-31 treated DNA be cloned?
  6. What is a good control for the BAL-31 nuclease?
  7. Will Nuclease BAL-31 degrade RNA?