Agarose Gel

Figure 36.4: DNA-Protein interaction analysis by agarose gel electrophoresis.

3. Electroelution-As discussed in previous lecture, protein band present within the polyacrylamide gel block is removed by electroelution for further usage (Figure 36.5). In the electroelution, a gel band is cut from the SDS-PAGE and placed in a dialysis bag and sealed from both ends. The dialysis bag is choosen so that the molecular weight cut off of dialysis membrane should be lower than the protein of interest. The dialysis bag is placed in the horizontal gel apparatus with buffer and electrophoresis is performed with a constant voltage. During electrophoresis the protein band migrate and ultimately comes out from the gel block. Due to dialysis bag, salt and other small molecule contaminant moves out of the dialysis bag but protein remain trapped within the dialysis bag. Protein can be recovered from the dialysis bag for further use in downstream processing.