Question: Are directly conjugated primary antibodies always the best choice? 

Answer: It depends on a few factors: 
  • Is the protein to be visualized highly abundant? 
  • Is the primary antibody to be labelled provided as affinity purified against the antigen? 
  • Can the primary antibody be used in experiments within the next couple of months?
For proteins of high and medium abundance, directly conjugated primary antibodies is a good choice, as it shortens the Western blot protocol, and, in case of primary antibodies conjugated to fluorophore, offers multiplexing possibilities.

The expression level of the target protein can be checked in the PaxDb; Protein Abundance Database. If the protein is of low abundance, enhancement of the signal provided by the secondary antibodies, is necessary for visualization.

Only primary antibodies that have been purified against the antigen (protein or peptide) are suitable for direct labeling. Antibodies provided in serum format, or as a total immunoglobulin fraction, are not suitable for direct labeling.

The shelf-life of directly conjugated primary antibodies may vary, and it is therefore advised to complete the experiments in a prompt manner.




  
Agrisera directly conjugated primary antibodies


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