Product Class: Ligase

Taq DNA Ligase



  • Isolated from a recombinant source
  • Thermostable ligase for incorporation of phosphorylated oligonucleotides during PCR and Ligase Chain Reaction
  • Taq DNA Ligase is NOT a substitute for T4 DNA Ligase
  • Supplied with 10X Reaction Buffer containing NAD+
Taq DNA Ligase is a thermostable ligase that catalyzes the formation of a phosphodiester bond between the 5´-phosphate and the 3´-hydroxyl of two adjacent DNA strands. The strands to be ligated need to be hybridized and accurately paired, with no gap, to a complementary DNA strand; allowing resolution of single nucleotide variants. Taq DNA Ligase uses NAD as a cofactor and it is active at elevated temperatures (37° C – 75° C).  

Product Source

Purified from an E. coli strain containing the cloned ligase gene from Thermus thermophilus HB8 (1-3).

Reagents Supplied

The following reagents are supplied with this product:

Store at (°C)Concentration
Taq DNA Ligase Reaction Buffer-20*10X

* Reagents' Storage Notes

  • Taq DNA Ligase Reaction Buffer: For long term storage (>30 days), store at -80°C.

Advantages and Features


  • Allele-specific gene detection using Ligase Detection Reaction and Ligase Chain Reaction (4).
  • Mutagenesis by incorporation of a phosphorylated oligonucleotide during primer extension amplification (5).

Properties and Usage

Unit Definition

(Cohesive End Unit)
One unit is defined as the amount of enzyme required to give 50% ligation of the 12-base pair cohesive ends of 1 µg of BstEII-digested λ DNA in a total reaction volume of 50 µl in 15 minutes at 45°C.

Usage Concentration

40,000 units/ml

Storage Temperature


Storage Conditions

10 mM Tris-HCl
50 mM KCl
1 mM DTT
0.1 mM EDTA
200 μg/ml BSA
50% Glycerol
pH 7.4 @ 25°C

Heat Inactivation


Unit Assay Conditions

1X Taq DNA Ligase Reaction Buffer and DNA (20 µg/ml). After incubation at 45°C for 15 minutes, the reaction is terminated by addition of stop dye (50% glycerol, 50 mM EDTA and bromophenol blue), heated at 70°C for 10 minutes and then loaded on a 0.7% agarose gel. Due to the presence of ligase, the cos ends of BstEII-digested λ DNA will stay together after 70°C heat treatment.

Heat Inactivated


Quality Control

Quality Assurance Statement

  • Each lot is tested for contaminating single-stranded DNA exonuclease, endonuclease, ribonuclease and phosphatase activities.

Quality Control Assays

The following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page. Further information regarding NEB product quality can be found here.
  • Endonuclease Activity (Nicking):
    The product is tested in a reaction containing a supercoiled DNA substrate. After incubation for 4 hours the percent converted to the nicked form is determined by agarose gel electrophoresis.
  • Exonuclease Activity (Radioactivity Release):
    The product is tested in a reaction containing a radiolabeled mixture of single and double-stranded DNA. After incubation for 4 hours the exonuclease activity is determined by the % release of radioactive nucleotides.
  • Non-Specific DNase Activity (16 hour):
    The product is tested for non-specific nuclease degradation in a reaction containing a DNA substrate. After incubation for 16 hours there is no detectable degradation of the DNA substrate as determined by agarose gel electrophoresis.

Supporting Documents

The Certificate of Analysis (COA) is a signed document that includes the storage temperature, expiration date and quality control's for an individual lot. The following file naming structure is used to name these document files: [Product Number]_[Size]_[Version]_[Lot Number]
The Specification sheet is a document that includes the storage temperature, shelf life and the specifications designated for the product. The following file naming structure is used to name these document files: [Product Number]_[Size]_[Version]
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. Reaction Conditions: Incubate DNA and enzyme in 1X Taq DNA Ligase Buffer at 45°C for 15 minutes or in a thermocycler with a program suited to the reaction described by Barany (1991) Genetic Disease Detection and DNA Amplification Using Cloned Thermostable Ligase. Proc. Natl. Acad. Sci. USA 88, 189-193. The reaction is stopped with a mixture of 50% glycerol, 50 mM EDTA, bromphenol blue.
  2. 1X Taq DNA Ligase Reaction Buffer requires NAD+ as a cofactor. NAD+ is supplied in the 10X Taq DNA Ligase Reaction Buffer; the buffer should be stored at -80°C to extend the half life of the NAD+ cofactor.


  1. Takahashi, M. et al. (1984). J. Biol. Chem.. 259, 10041-10047.
  2. Barany, F. (1991). Proc. Natl. Acad. Sci. USA.. 88, 189-193.
  3. Barany, F. and Gelfand, D.H. (1991). Gene.. 109, 1-11.
  4. Barany, F. (1991). The Ligase Chain Reaction in a PCR World.. 5-16.
  5. Michael, S.F. (1994). Biotechniques.. 16, 411-412.
  1. Is Taq DNA Ligase used for a special technique?
  2. How much ligation occurs at mismatches when using Taq DNA Ligase?
  3. How many temperature cycles will Taq DNA Ligase survive?
  4. Can Taq DNA Ligase be used for cloning?
  5. What is the molecular weight of Taq DNA Ligase?
  6. Why is the Taq DNA Ligase buffer brown?
  7. Does Taq DNA Ligase require NAD?
  8. What is the activity of Taq DNA Ligase in other NEBuffers?
  9. What is the activity of Taq DNA Ligase at various temperatures?
  10. What is the stability of Taq DNA Ligase at 95°C?
  11. What is the stability of Taq DNA Ligase at room temperature?
  12. What is LCR and which enzymes do you recommend?
  13. What is LDR and how does it differ from LCR?
  14. How can I design probes for LDR or LCR to maximize specificity?
  15. Do thermostable DNA ligases (such as Taq DNA Ligase, 9°N DNA Ligase, and HiFi Taq DNA Ligase) ligate sticky ends?
  1. Protocol for Taq DNA Ligase (M0208)

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