It is good practice to dialyse, or alternatively use a de-salting column on FPLC, but I would be more concerned about the purity of your antigen. Histidine can be found in many proteins, and purification of His-tagged proteins on a nickel chelate column and elution with imidazole should be regarded as the first step. One should really check the eluate on SDS-PAGE and load sufficient material so that contaminating bands of different molecular weights show up in the coomassie or silver stain. Contaminating bands can be easily depleted by doing an ion-exchange chromatography run to isolate the major peak (hopefully the His-tagged protein), this will also concentrate the recombinant protein in a narrow peak, and then you can either raise antibodies to the native protein, or against the denatured protein (depending on what you want to use the antibody for, i.e. immunoprecipitations, western blots, immuno-detection in EM or lfluorescent microscopy).
Depends what else is in your protein preparation. As long as it's considered non-toxic, I'd just go ahead.
Nevertheless, I would dialyse it against an appropriate dialysis buffer to remove the imidazole and everything else that could disturb the antibody production or harm the animal.
HEre, you can find nice information about dialysis:
http://www.piercenet.com/method/dialysis-methods-protein-research
It is good practice to dialyse, or alternatively use a de-salting column on FPLC, but I would be more concerned about the purity of your antigen. Histidine can be found in many proteins, and purification of His-tagged proteins on a nickel chelate column and elution with imidazole should be regarded as the first step. One should really check the eluate on SDS-PAGE and load sufficient material so that contaminating bands of different molecular weights show up in the coomassie or silver stain. Contaminating bands can be easily depleted by doing an ion-exchange chromatography run to isolate the major peak (hopefully the His-tagged protein), this will also concentrate the recombinant protein in a narrow peak, and then you can either raise antibodies to the native protein, or against the denatured protein (depending on what you want to use the antibody for, i.e. immunoprecipitations, western blots, immuno-detection in EM or lfluorescent microscopy).
Its always better to dialyze the protein before immunization or even before storage as it aids in removal of imidazole that has been used for elution as welll as other salts that has been used during purification. Or you can try Zeba desalting columns for pierce that can also solve the purpose but I will recommend overnight dialysis against PBS.
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