Protein construct: Wild-type E. coli NAD+ -dependent DNA Ligase purified from a bacterial expression system.
MW: 74 kDa
Enzyme concentration: 500 nM
Enzyme activity assay: The DNA Ligase activity is measured by using the NAD+ -dependent DNA Ligase Assay Kit (Catalog No. NLA100K).
Storage temperature: -20 or -80°C. Do not freeze-and-thaw repeatedly.
Enzyme dilution: Use the 1 x assay to dilute the enzyme just before the assay. Do not store diluted enzyme solution.
The E. coli NAD+ -dependent DNA Ligase – for 100 assays (Catalog number LIG-100EC) includes10 µl of 500 x E. coli ligase (500 nM). It is for 100 assays.
Assay Protocol using the NAD+ -dependent DNA Ligase Assay Kit
1. Reagent preparation:
10 x DNA: dilute the 100 x DNA with water
100 x enzyme: 100 nM NAD+ -dependent DNA ligase
0.1 mM NAD+ : dilute the 10 mM stock with water
1 x fluorescence dye: dilute the 10 x fluorescence dye 10-fold with water
2. Reaction:
The total volume of each reaction mixture is 40 µl including: 27.6 µl of H2O, 4 µl of 10 x buffer (Buffer LS), 4 µl of 10 x DNA, 0.4 µl of 100 x enzyme, and 4 µl of 0.1 mM NAD+ . Incubate the reaction mixture at 37°C for 60 min.
3. Detection:
Add 200 µl of Reagent T into the 40 µl of reaction mixture. Then add 20 µl of the 1 x fluorescence dye. Mix the reaction solution and incubate it for 15 min. Measure the fluorescence intensity at 535 nm using the excitation wavelength at 485 nm.