Knight:NuPAGE electrophoresis

In progress! For a better version of this protocol, see Sauer:bis-Tris SDS-PAGE, the very best.

Purpose

To run a denaturing protein gel. Note that a preferable version of this protocol is available at Sauer:bis-Tris SDS-PAGE, the very best (recommended by Kathleen). But since we seem to already have the Invitrogen kit contents in lab, this protocol describes use of the Invitrogen system.

Materials

• NuPAGE Novex 10% Bis-Tris Gel 1.0 mm, 10 well
• XCell SureLock Mini-Cell electrophoresis apparatus
• 20X MES Running Buffer
• NuPAGE LDS Sample Buffer (4X)
• NuPAGE Reducing Agent (10X)
• NuPAGE Antioxidant

Procedure

Sample preparation

1. Wells can accommodate 25μL loading volume.
2. Let sample buffer warm to room temperature.
3. Each sample should contain
   • 13 μL protein sample (max 0.5μg per band)
   • 5 μL NuPAGE LDS Sample Buffer
   • 2 μL NuPAGE Reducing Agent
4. Heat samples at 70°C for 10 mins.
5. Note that prestained molecular weight marker doesn't need any preparation.

Running buffer preparation

1. Prepare 1000mL 1X NuPAGE SDS running buffer
   • 50mL 20X MES Running Buffer
   • 950mL deionized water
2. Mix well.
3. Set aside 200mL buffer for use in Upper (Inner) buffer chamber).
   • Add 500μL NuPAGE Antioxidant immediately before use.
   • Mix well.

Running the gel

1. Wear gloves.
2. Remove the NuPAGE gel from the pouch.
3. Rinse the gel cassette with deionized water.
4. Peel the tape from the bottom of the cassette.
5. Gently pull the comb from the cassette in one smooth motion.
6. Rinse the sample wells with 1X NuPAGE SDS running buffer.
7. Invert and shake to remove buffer.
8. Repeat rinse two more times.
9. Orient the two gels in the Mini-Cell such that the notched "well" side of the cassette faces inward towards the buffer core.
10. Seat the gels on the bottom of the Mini-Cell and lock into place with the gel tension wedge.
    • Use the plastic buffer dam if you are only running one gel.
11. Fill the upper buffer chamber with a small amount of uppder buffer chamber running buffer (with antioxidant) to check tightness of seal.
    • If there is a leak, discard buffer, reseal chamber and try again.
12. Fill upper buffer chamber. Buffer level should exceed level of the wells. Requires about 200mL
13. Load samples.
14. Load protein molecular weight marker.
15. Fill lower buffer chamber with 600mL NuPAGE SDS running buffer.
16. Run at 200V for 35 minutes.

References

1. NuPAGE Technical Guide