Antigen Requirements

We accept proteins, peptides (conjugated or unconjugated), enzymes, heat-killed bacteria and viruses, cells, etc. If providing a fusion protein made using a large fusion partner such as GST or MBP, we recommend cleaving the fusion partner prior to submitting the protein for immunization. Large fusion partners tend to be highly antigenic and can dilute the resulting polyclonal antibodies or make screening difficult for monoclonal development. We also recommend than any antigen with a molecular weight of less than 10kDa be conjugated to a carrier protein to make it large enough to be recognized by the host animals’ immune systems. Please complete our Antigen Submission Form before submitting your antigen. Also make sure to check out our Antigen Requirements Infographic by clicking on the image below.

Antigen quantities

We can start a custom polyclonal antibody production project with 50% of the total amount of antigen needed; additional quantities can be sent during the project’s progress.

Antigen Requirements Graphic

Antigen Purity

Generally, peptide antigens need to be around 70% purity or greater and protein antigens need to be at least 90% purity or greater. The necessary antigen purity also depends upon what you are trying to do with your project. For polyclonal antibodies, >70% peptide antigen purity is fine, but for monoclonal antibodies, >90% antigen purity is the standard. Additionally, peptide antigens containing modified amino acids should also be >90% purity even for polyclonal antibody development.

Antigens in Solution:

They should be submitted at a concentration of 1mg/mL or higher (please specify the concentration, total volume, and total amount). Precipitation is not problematic for use in immunization for custom polyclonal antibody production. We need to know the buffer components that the antigen is in (PBS, Tris, < 4M urea are preferred); SDS and citrate buffers are also acceptable. Please note for services such as ELISA and immuno-affinity purification the antigen needs to be soluble, and for immuno-affinity purification the protein cannot be in Tris or other buffers with primary-amines.

Lyophilized Antigens:

We need to know the total amount of antigen contained, if there is a preferred storage temperature (4°C, -20°C, -80°C), and if there are any specific reconstitution steps needed.

Gel Strips as Antigens:

Proteins can be submitted as a gel strip, cut from an SDS PAGE gel. Please note that we cannot perform an affinity purification or ELISA when the protein is supplied in this form. The protein needs to be reasonably concentrated (2-5 mg/mL) and then run into the gel. If it precipitates, use a lower concentration. 100 to 200µg of protein in 500µL of gel is the maximum we can inject into rabbits. Stain the whole strip with coomassie blue then de-stain it, rinse with water at least twice to remove traces of methanol, and cut the desired strip from the gel. Place the strip in a 15 or 50mL conical vial with water and ship with an icepack – don’t freeze it.

When submitting your antigen, please complete the Antigen Submission Form (PDF).

Please contact us at or call 888-513-9525 if you are uncertain about any of the antigen requirements for custom polyclonal antibody production. You can also fill out the following form. 

Not Sure About Your Antigen?