SE 660 Dual Cooled Vertical Unit, Basic, for 18 × 24 cm plates

Why is the electrophoresis run on the vertical gel unit running unusually slow or fast?

There are several possible causes for an unusually slow or fast run on a vertical electrophoresis unit:

1. Current leakage around gel. Check for leaks, all plates and spacers must be aligned and free of grease and cracks. If using SE600, make sure that buffer dam is used and assembled properly.

2. Sample or reagent preparation.

3.Voltage or current settings. To increase or decrease the migration rate, adjust the voltage or current by 25 - 50%.

Why is my electrophoresis run taking longer/shorter than usual?

1. Decrease the salt concentration of samples.

2. Adjust the solutions:
a. Check recipes, gel concentrations, and solutions. (For instance, do not use Tris-HCI instead of Tris base.)
b. If proteins move too fast dilute the buffer so that less current will be carried.
c. If proteins move too slow, increase the buffer concentration so that more current will be carried.
d. If the required pH of a solution is exceeded, do not back-titrate. Prepare fresh buffer.
e. Dispose of older acrylamide solutions and use only stock of the highest quality.
f. Only use freshly deionized urea.

3. Adjust the voltage or current settings: To increase or decrease the migration rate, adjust the voltage or current by 25 - 50%.

4. Electrical leakage.
a. Check the alignment of the glass plates and spacers. Make sure there is no dirt or grease on the plates or spacers, and no cracks in the glass.
b. Check the heat-exchanger for leakage around the grommets.

5. Sample protein bands run slow but the marker bands are running fine.
a. The sample probably contains some nonionic (or cationic) detergent that is competing with the SDS (Sodium dodecyl sulfate) to coat the proteins. It is the negative charge of SDS that causes the proteins to migrate to the anode. Samples with Triton X-100 will lower the charge density and cause the sample proteins to migrate slower. The markers, coming out of a separate vial, probably don't have the Triton and will therefore migrate correctly. The solution is to clean the sample to remove the nonionic detergent (try TCA (Trichloroacetic acid)-acetone precipitation or the SDS-PAGE Clean-Up Kit).

Can I store cast gels?

To store unused gels add approximately 5.0 ml of 1X separating gel buffer to the top of each sandwich, seal with plastic wrap (or heat-seal into a bag), and lay flat in refrigerator set to 4 °C. Or, lay gels flat in a Pyrex baking dish, submerge in 1X separating buffer, and store refrigerated. Use within 1 week.