What Types of Antigens Can be Used to Manfacture a Polyclonal Antibody?Antibodies can be made from expressed or native protein, proteins separated by gel electrophoresis and the appropriate band excised, chromatographically purified tryptic peptides, heat or formaldehyde-inactivated viruses, and synthetic peptides. The use of synthetic peptides, owing in part to their minimal cost and purity, can be used to produce antibodies in a variety of species (e.g., rabbit, goat, sheep, mouse, rat, chickens). In addition, during the synthetic process, post-translational modifications (PTMs) can be added at specific site(s) along the peptide chain, allowing for the production of antibodies selective not only for the peptide's primary sequence, but for one or more PTMs as well. The most common PTM studied with the use of specific antibodies is phosphorylation. The scientists at 21st Century Biochemicals have many years of experience producing antibodies selective for the phosphorylation state of the peptide as well as the parent protein.