How are peptides coupled to carrier protein?
We highly recommended customers provide us with or synthesize a peptide with an N- or C- terminal cysteine. In the absence of internal cysteines in a given peptide, the most common and efficient means of coupling peptides to a carrier protein is through the SH group of a terminal cysteine residue. Usually the cysteine is added to the N-terminus of the peptide for the most efficient conjugation, however if the peptide antigen is from the N-terminus of the protein the cysteine can be added at the C-terminus of the peptide to more closely mimic the conformation of native epitopes. If it is not possible to avoid an internal cysteine in the peptide antigen, alternative conjugation chemistries can be used. Please contact our customer support if you have to choose this option. Conjugation can be done through the N-terminal NH2 group or C-terminal COOH group, though with lower efficiency, as long as internal amino acids containing free NH2 or COOH groups, respectively, are avoided.
