Purification of mAb (IgG)
互联网
Purpose
Materials
- Antibody 7E3 , 2L sup grown in flasks, frozen and thawed overnight.
- BioRad Affi-Gel Protein A MAPS II Buffers cat. #1530-6160 ($161.00)
- 50 mM Tris pH7.8
- 40 g ammonium sulfate for every 100 ml Sup.
- 4L 100 mM Tris/pH7.8 or Binding Buffer
- BD tubing 14-170-12F (Fisher)
- Polyethylene tubing Clay Adanes.
- 18 Gauge needles.
- Binding Buffer (BioRad): make 1L. 314g/L ddH2 O and filter through 0.22 um, filter. pH=9.0
- Elution buffer (BioRad): make 500 ml. 11g/500 ml ddH2 O and filter as before. pH=3.0
- Regeneration buffer (BioRad): BioRad Affi-gel regeneration buffer.
Procedure
For Ammonium sulfate cut:- Filter Sup. in 1L Costar Filter using pre-filter.
- Add 50 mM Tris pH7.8 (50 ml of 1 M stock/Liter). 100ml
- Add 40 g ammonium sulfate for every 100 ml Sup. (slowly). 800g
- Stir O/N in cold room.
- Pour into plastic bottles. Spin at 4 o C, 7,500 rpm for 20 min in JA-10 rotor.
- Prepare 4L 100 mM Tris/pH7.8 (400 ml of 1 M stock/4 L) or Binding buffer .
- Discard Sup. Resuspend pellets in 10 ml of 100 mM Tris buffer or Binding buffer . And pool into 50 ml Falcon tubes (try not to make bubbles).
-
Use 3.2 ml/cm 12-14,000 MW dialysis tubing.
- Heat tubing in 500 ml H2 O in microwave. Not boiling.
- Rinse tubing in fresh H2 O several times.
- Test each tube w/H2 O and discard.
- Add protein mixture to dialysis tube. Stir slowly in 100 mM Tris buffer or Binding buffer until pink color is out.
- Transfer protein mixture (Ab) to 50 ml Falcon tubes to determine volume.
- Dilute the mixture 1:1 with Binding buffer .
- Filter through 0.45 um filters (use prefilters).
- Prepare Protein A column.
- Run binding buffer (pH9.0) ~ 200 ml.
- Filter protein mixture
-
Add protein mixture or culture supernatant containing Ab (adjust pH to 7.8 with Binding buffer ; red color) to the Protein A column.
Mouse antibodies of the IgG1 subclass do not have a high affinity for protein A. Purification on protein A beads using standard conditions will yield approximately 1/10 the amount of antibody compared with other subclasses. In case of IgG1 subclass, add 3.3 M NaCl (192.85 g/L) to crude antibody preparation (serum, tissue culture supernatant, or ascites).
- Apply Binding buffer again ~ 200 ml.
- Apply Elution buffer ~ 100 ml.
- Collect 3 ml fractions in 5 ml tubes with 700 ul 1 M Tris pH 9.0 already in bottom of tube to neutralize (collect at ~5 min/fraction).
- 25 tubes are sufficient for collection. In general, you can see high Ab concentrations in 7-8 tubes.
- Test 1 ul on pH paper.
- Read OD to know Ab concentrations.
- OD (Absorbance at 280 nm)/1.35 = X mg/ml.
- Store Abs at -20o C or further concentrate by using Centriprep. And store at -20o C.
- Regenerate Ab column with Regenerate buffer (~200 ml).