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Preparation for Gradient Gel Casting Hoefer DALT System
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Amersham Biosciences
Preparation for Gradient Gel Casting
Successful gel casting requires planning, timing and practice.
A full DALT Gel Caster requires approximately two liters of acrylamide stock.
Polymerization begins as soon as you add TEMED and APS to the acrylamide stock.
Once you have added these reagents, there is no time to adjust the gradient maker
divider, or the cassettes and separators in the gel caster.
To familiarize yourself with the gel caster and gradient maker before casting gels, we
recommend you set up the unit, as described on page 12, and configure the gradient
divider, as described on this page. Follow the gradient pouring procedure on page 18,
substituting water for the appropriate volume of light solution, and a mixture of
glycerol and water for the appropriate volume of heavy solution.
When the angle of the gradient divider is correctly adjusted and you are comfortable
with the gel casting procedure, clean all parts of the caster and gradient maker, including
sponges, separating sheets and filler blocks, with a solution of mild detergent, followed
by a fresh water rinse.
Configuring the Gradient Divider
You can adjust the shape of the gradient divider to suit the number of gels to be cast and
shape of the gradient you want. When casting a full tank of gels, the angle of the
adjustable divider to the floor of the gradient maker should be about 70 °. For fewer
gels, decrease the divider angle (Figure 9). Whatever angle you use, a straight divider
gives a linear gradient.
Figure 9. Gradient divider
configurations for half-full
and full Gel Caster tanks.
1. Determine the amount of gel solution needed to cast the desired number of gels.
2. Loosen the faceplate screws on the empty gradient maker to adjust the gasket angle.
Refer to the divider configurations in Figure 9 as a guideline to the angle you should
use.
Pull the divider slightly to help move it into position. Use the red adjuster rod
provided with the gradient maker to push the gradient divider down.
Divider angle (approx.) 40 ° 50 ° 60 ° 70 °
Number/thickness 12 gels/1.0 cm 12 gels/1.5 cm 25 gels/1.0 cm 23 gels/1.5 cm