Overview
In this video, we demonstrate the nickel affinity chromatography technique to purify histidine-tagged pyrophosphokinase enzymes from Clostridium difficile bacteria.
Protocol
1. Protein Purification by Nickel Affinity Chromatography
- Purify protein using 1 mL of Nickel-Nitriloacetic Acid (Ni-NTA) resin on a gravity column.
- The day before use, equilibrate the column overnight at 4 °C with 2 mL of equilibration buffer (10 mM Tris-HCl pH 7.79, 300 mM NaCl, 50 mM NaH2PO4, 0.5 mg/mL lysozyme, 5 mM MgCl2, 10 mM imidazole, 0.25 mM DTT, 5 mM phenylmethane sulfonyl fluoride (PMSF), 10% glycerol).
- The following day bring the column from 4 °C to RT prior to loading the clarified lysate and let it stand for ~2–3 h.
NOTE: Bringing the column to thermal equilibrium is crucial to avoid air bubbles forming within the column. - Resuspend the pellet in the lysis buffer (10 mM Tris-HCl pH 7.8, 300 mM NaCl, 5 mM MgCl2, 50 mM NaH2PO4, 10% glycerol, 0.5 mg/mL lysozyme, 10 mM imidazole, 0.25 mM DTT and 5 mM PMSF).
- Sonicate cells on ice for 8 x 10 s intervals, pausing 30 s between pulses.
- Clarify the lysate by centrifugation at 3,080 x g for 30 min at 4 °C using a microcentrifuge.
- Prepare lysate with equal volumes of lysis buffer then apply the prepped clarified lysate to the column and collect the flow-through.
- Reapply clarified lysate flow-through to the column and collect the secondary flow-through.
- Wash the column with wash buffer 1 (10 mM Tris-HCl (pH 7.79), 300 mM NaCl, 5 mM MgCl2, 50 mM NaH2PO4, 30 mM imidazole, 10% glycerol). Collect the flow-through.
NOTE: Inclusion of 5 mM MgCl2 in the wash and elution buffers is important for enzymatic activity of the purified protein. - Wash the column with wash buffer 2 (10 mM Tris-HCl (pH 7.79), 300 mM NaCl, 5 mM MgCl2, 50 mM NaH2PO4 and 50 mM imidazole).
- Collect the flow-through.
- Apply 2 mL elution buffer (10 mM Tris-HCl (pH 7.79), 300 mM NaCl, 50 mM NaH2PO4, 10% glycerol and 75 mM imidazole). Collect flow-through in two fractions of 1 mL each.
NOTE: The column after this step can be stored in equilibration buffer at 4 °C if the same protein will be purified in the next purification assay. The column can be used up to 3 times if stored properly.
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Materials
Name | Company | Catalog Number | Comments |
Ni-NTA resin | G Biosciences | 786-940/941 | |
Pierce Disposable Gravity columns, 10 mL | Thermo Scientific | 29924 | |
1 mL Spectra/ Por float-A-lyzer G2 dialysis device (MWCO: 20-kD) | Spectrum | G235033 | |
Ultrasonic processor | Sonics | VC-750 | |
Microcentrifuge with D3024/D3024R rotor | Scilogex |