What should I consider before ordering synthetic peptide-carrier protein (KLH, BSA) conjugates?
• Purity of peptides to be conjugated to the carrier protein – While many researchers prefer coupling of the highly purified (>95%) peptides, others use less pure and less expensive materials (>75% or >85%) with reportedly good results. • Method of conjugation to the carrier protein – A coupling through a SH group of Cysteine residue or through the N-term amino group (with glutaraldehyde) are the most common, with the approximate occurrence ratio of 9:1. In the absence of the naturally occurring Cysteine in the peptide of interest, an extra Cysteine may be added to the sequence at either N-term or C-term to serve as an attachment point. With the glutaraldehyde mediated coupling, the best results are attained in the absence of the internal Lysine in the sequence, as the side amino group of it would also react. Generally, it is believed that conjugation involving Cysteine produces better-defined product.
