Each antibody is different, some might last for 20-40 years, while other antibodies will have quite a short life of one year. Storage conditions are of importance to extend antibody life, however the stability of each specific antibody might be different. Therefore, please follow the information provided on the specific product information sheet for each antibody. What works for one antibody, might not necessarily be applicable for another one. This is very important to keep in mind. If it is not clear ，pleasecontact us. General recommendations for antibody storage can be found here.
It does not matter from which species the primary antibody comes from for a western blot application. There are many good secondary antibodies available for any of those species you inquire about.
What is important is to which part of a protein an antibody is made to. Is it going to recognize epitopes (stretches of 2-3 amino acids) which are exposed on a given protein after transfer to a membrane? Some proteins can refold following the transfer, depending upon applied conditions, which can make a given epitope not accessible. It also depends on if the western blot is performed in native or denatured conditions. The addition of 6-8 M urea to your loading buffer might help to keep your protein unfolded and accessible for an antibody to bind.
Before you use an antibody in western blot, please check to which part of the protein it was made. Are there any references which confirms the use of this antibody for this specific technique?
Again, it depends upon the antibody binding place on the protein. Is this part exposed after fixation or following the western blot? If a polyclonal antibody is made to a synthetic peptide, it is recognizing a pool of epitopes (linear epitopes are streches of 2-3 amino acids)and if such epitopes are not exposed following fixation: the antibody is not going to work.
Not really, it all depends upon the conservation level of a specific peptide used to elicit this antibody. It can be checked by comparing the peptide used to elicit this antibody and your protein sequence. The conservation level between the peptide used to make an antibody and the peptide found in your protein seqence needs to be around 80 %, to allow an antibody to work in case of anti-peptide antibodies and can be lower for antibodies made to larger parts of a protein. In some cases 6-8 M urea needs to be included to fully unfold the protein. The electrophoretic mobility of a protein can also vary between different species.
Have you checked recommended conditions to use for this specific antibody, included on the product info sheet? Some antibodies will work reasonably well and give good results regardless of the applied conditions, like membrane type, load per well and developing reagent. Some antibodies will actually require a bit more consideration. Less backgrond can be obtained for some antibodies when using pvdf vs. nitrocellulose membrane for transfer or by applying recommended blocking. There are also variations between secondary antibodies. At least, but the most important, is the type of sample you are analyzing. You can eithercontact us or check our Western blot trouble shooting, it can be found here.
Usually the C or N-terminal of the protein is used, as those parts of protein are exposed. Also, to mimic protein behavior, the synthesized peptide should have similar structure and charge as the protein it has been "cut out off". Therefore:
- peptides derived from the C terminal should have N terminal modified by acetylation
- peptides derived from the N terminal should have C terminal modified by amidation - peptides derived from an internal sequence should have both ends modified
Following points should also be considered:
- Are there any other proteins from the family of interest, where cross-reactivity should be avoided?
- Is the crystal structure of the protein (or homologous protein) known? This would be helpful for the peptide chemist in searching for the best peptide for antibody production.
- What is the final application of the produced antibodies? Native or denatured techniques?