T4 DNA Ligase Buffer
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T4 DNA Ligase Buffer
Invitrogen™

T4 DNA Ligase Buffer

T4 DNA Ligase catalyzes the formation of phosphodiester bonds in the presence of ATP between double-stranded DNAs with 3´ hydroxylRead more
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Catalog number 46300018
Price (USD)
71.00
Each
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Price (USD)
71.00
Each
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T4 DNA Ligase catalyzes the formation of phosphodiester bonds in the presence of ATP between double-stranded DNAs with 3´ hydroxyl and 5´ phosphate termini. The unique T4 DNA Ligase buffer optimizes ligation, which can be performed in 5 minutes (1). Single-stranded nucleic acids are not substrates for this enzyme. A T4 DNA Ligase Technical Bulletin is available.

Applications: Cloning (blunt-end or cohesive-end ligation) (2). Adding linkers or adapters to blunt-ended DNA (2).

Source: Purified from E. coli œ lysogen NM989.

Performance and Quality Testing: Endodeoxyribonuclease, 3´ and 5´ exodeoxyribonuclease assays; ligation efficiency tested.

Unit Definition: One unit catalyzes the exchange of 1 nmol 32P-labeled pyrophosphate into ATP in 20 min. at 37°C. (One unit is equal to approximately 300 cohesive-end ligation units.)

Unit Reaction Conditions: 66 mM Tris-HCl (pH 7.6), 6.6 mM MgCl2 , 10 mM DTT, 66 μM ATP, 3.3 μM 32 P-labeled pyrophosphate, and enzyme in 0.1 ml for 20 min. at 37°C.
For Research Use Only. Not for use in diagnostic procedures.
Specifications
Shipping ConditionApproved for shipment on Wet or Dry Ice
Compatible Buffer5X Reaction Buffer
Quantity2 x 1 mL
Product TypeT4 DNA Ligase Buffer
Unit SizeEach
Contents & Storage
T4 DNA Ligase is supplied with a vial of 5X reaction buffer [250 mM Tris-HCl (pH 7.6), 50 mM MgCl2 , 5 mM ATP, 5 mM DTT, 25% (w/v) polyethylene glycol-8000]. Store at -20°C.

Frequently asked questions (FAQs)

What are common inhibitors of the T4 DNA ligase?

dATP is a competitive inhibitor. Phosphate will reduce ligation efficiency. Detergents in your ligation buffer will likely not affect activity. High levels (0.2M) Na2+, K+, Cs+, Li+, and NH4+ inhibit the enzyme almost completely. Polyamines, spermine, and spermidine also serve as inhibitors.

Do both my insert and vector have to be phosphorylated for successful ligation?

At least one molecule in a ligase reaction (i.e., insert or vector) must be phosphorylated. Ligation reactions are dependent on the presence of a 5' phosphate on the DNA molecules. The ligation of a dephosphorylated vector with an insert generated from a restriction enzyme digest (phosphorylated) is most routinely performed. Although only one strand of the DNA ligates at a junction point, the molecule can form a stable circle, providing that the insert is large enough for hybridization to maintain the molecule in a circular form.

Which T4 DNA Ligase protocol do you recommend when ligating an insert containing one cohesive (sticky) end and one blunt end?

For cloning an insert with one cohesive end and one blunt end, use the conditions for blunt ends.  The sticky end may ligate quickly, but the blunt end ligation will still be inefficient. You should use the more stringent protocol to optimize the blunt end ligation. This usually means using more enzyme (5 U), a lower reaction temperature (14C) and a longer incubation time (16-24 hours). 

Why is it necessary to dilute ligated DNA products before adding them to competent bacterial cells?

Components of the ligation reaction (enzymes, salts) can interfere with transformation, and may reduce the number of recombinant colonies or plaques. We recommend a five-fold dilution of the ligation mix, and adding not more than 1/10 of the diluted volume to the cells. For best results, the volume added should also not exceed 10% of the volume of the competent cells that you are using.

What are the recommended conditions for blunt-ended ligations?

Generally, ligations are done in a 20 µL volume. Use a total of 100 to 1000 ng of DNA with an insert to vector ratio of 3:1. Add 1.0 units (Weiss) ligase to the reaction. Incubate at room temperature for 4 h or overnight at 14-16 degrees C.

Ideally, assemble several reactions with varying ratios of vector:insert (i.e. 3:1, 5:1, 10:1, 20:1, etc.) to determine the optimal ratio for ligation.

Thermo Fisher Scientific offers T4 DNA ligase at two concentrations: 1 U/µL (Cat. No. 15224-017) and 5 U/µL (Cat. No. 15224-041). When performing blunt or TA cloning ligations, the higher concentration of ligase is generally preferred since ligating a blunt or single base overhang requires more enzyme.

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