Proteins are naturally occurring biological molecules formed of longer chains of amino acids linked by peptide bonds. Proteins are ubiquitous expressed in cells and play a critical role in biochemical reactions within cells, they regulate metabolism and they provide structural support. Alteration in proteins expression or their wrong folding can be the cause of many diseases and the understanding of proteins behaviour is crucial for the better understanding of how diseases develop and for the development of diagnostic and therapeutic strategies and tools.
Full length proteins are strong immunogens and can generate antibodies against several epitopes within the protein increasing the probability that antibodies against at least one of these epitopes will bind with the native protein in the target assay. Proteins can be provided in many forms such as full length, fragment, recombinant, fusion, gel band, etc. If a recombinant protein is available, it is the most recommended antigen; however, if the protein is not accessible it can prove to be more expensive if the recombinant protein has to be generated. The use of proteins as antigen can also increase the probability that antibodies against some of the protein epitopes could recognize other proteins in the sample that contain homologous epitopes resulting in non-specific cross reactivity.
When the target protein is not available or when only a specific portion of it has to be studied, it is necessary to synthesize specific pieces of the protein. Peptides are short chains of amino acid monomers linked by peptide bonds. They can be synthesized from, carefully chosen, sequences of the native protein and are used as immunogen instead of the protein. The protein amino acid sequence is analyzed and the appropriate sequences for peptides are selected according to criteria such as capacity of raising a good immune response, stability of the peptide or defined functional regions.
Antibodies generated against peptides have lower probability of cross-reactivity and there is no need for expression of the protein. Peptides are ideal to generate antibodies against posttranslational modifications (phosphorylations, cleavage products, etc) or to generate antibodies against one specific protein isoform or a specific member of a family of proteins.
We stand ready to work with you, whether for protein or peptide. Let us tailor the antigen to meet your individual project needs. Please, contact us. to obtain more information.