Bio-Rad PROTEAN Plus Multi-Casting Chamber - Manual (Page 8)

Note: GRADIENT GELS ONLY - the size of the V-shaped groove at the base of the multi-
casting chamber has been optimized for casting twelve gels. The size of the groove was
optimized so that the monomer solution enters all of the hinged spacer plates at the same
time, rather than one at a time (wicking). However, the larger dimension increases the amount
of monomer solution required to fill the V-groove, thus slightly altering the actual gradient
formed in the gels. With this is mind, TWO solutions are recommended:
• Adjust the heavy solution by approximately 0.5% to help compensate for the
V-groove. For example: If 8–16% linear gradient gels are being cast, prepare 16.5%
acrylamide/Bis for the heavy solution. (see sample calculation below in Section 3.2.2)
• Adjust the amount of light and heavy solution so that they are not equal.
For example: If the total volume required to cast twelve 4–20% gradient gels is 1100 ml,
prepare 555 ml of the light monomer solution (4%) and 545 ml of the heavy monomer
solution (20%). (See sample calculation in Section 3.2.2 and technical directions in
Section 3.2.6)
3.2.1. Place the gradient former on a magnetic stir plate and add a stir bar to the chamber
labeled "light". (See Section 2.2 for inlet port preparation) Place the gradient former
outlet above the top of the plate set, but minimize the length of tubing between it and
the multi-casting chamber.
Fig. 3. Proper set-up to cast 12 gradient gels.
3.2.2. Prepare the heavy and light monomer solutions.
6