Bio-Rad Whole Gel Eluter and Mini Whole Gel Eluter - Manual (Page 8)

Tube Rack
The tube rack forms a stable base for the harvester as well a housing for the collection
tubes. The rack is numbered for easy identification of fractions.
Lid and Needle Array
The lid fits onto the base only one way for proper alignment of the harvester needles with
the collection tubes. Connected to the lid by tubing is the needle array. The needle array inserts
into the harvest ports on the left side of the eluter. Thumb screws hold the needle array in
place, forming a seal between the array and the eluter. The array is designed to be inserted into
the eluter collection ports only one way for proper alignment during harvesting.
Vacuum Control Valve
The vacuum control valve is attached to the lid of the harvesting unit. The valve can be
gradually adjusted to increase or decrease the vacuum preventing uneven harvesting and splat-
tering of eluates.
Section 3
Assembly and Operation
3.1 Preparative Slab Gel Electrophoresis
The Whole Gel Eluters can accommodate SDS or Native PAGE preparative gels up to 3
mm thick. Gel thickness can have a major effect on the elution and recovery efficiency of
proteins. In addition, proteins not eluted into a buffer containing SDS, may adhere to the cel-
lophane (or dialysis) membrane. The thicker the gel, the longer it will take to elute the pro-
teins and the longer they will be in contact with the membrane. Protein recovery can be greatly
improved by reversing the current for 10 to 15 seconds after elution and by keeping elution
times down to a minimum.
1. Run the SDS or Native gel with a preparative comb following standard electrophoresis
procedures. Refer to Sections 6–7 and References for information on running SDS and
Native PAGE gels. The Mini Whole Gel Eluter requires a preparative gel with a minimal
width of 6.5 cm and the large format eluter requires a minimal width of 14.5 cm. The
length of the gel is not critical. It is acceptable for some unused elution chambers to be left
empty. It is convenient to have a lane of prestained standard proteins adjacent to the
preparative well to facilitate alignment of the cutting template, but this lane must be cut
off before placing the gel in the eluter.
2. Make up a liter of elution buffer for the Whole Gel Eluter and 500 ml for the Mini Whole
Gel Eluter. This buffer will be used to equilibrate the preparative slab gel and for the sub-
sequent eluter assembly. Refer to Sections 4.1 and 7.4 for elution buffer selection.
3. Following electrophoresis, remove the gel from the gel cassette and equilibrate it in elu-
tion buffer for 15–20 minutes. This is to allow an exchange of buffers and minimize
swelling of the gels during elution.
3.2 Whole Gel and Mini Whole Gel Eluter Assembly
One of the most important factors in the successful use of the Whole Gel Eluter is the
assembly of the unit. As with blotting techniques, it is vital to remove and (or) prevent bub-
ble formation under the gel. Second, proper alignment of the protein bands parallel to the elu-
tion chambers enhances selectivity.
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