Peptide antigens are often too small to generate significant immune responses on their own.
To solve this problem, these peptides are conjugated to bigger carrier proteins, such as bovine serum
albumin (BSA), ovalbumin, or keyhole limpet hemocyanin (KLH). One of the advantages of KLH is that it does
not interfere with ELISA or western blotting because it is not used as a blocking reagent. One common means
of conjugation method is the maleimide method, which couples the cysteine residue of the peptide to the
carrier protein. To perform this conjugation, one cysteine residue is added to the N- or C-terminus of the
peptide so that it may be linked to the carrier protein.
Note: KLH is a large (MW = 4*105 to
Because of its size and structure, its solubility in water is often limited, giving solutions and
a cloudy appearance. This does not affect immunogenicity and the turbid solution can be used for
immunizations. To avoid further confusion, we'll ship the peptides as solutions chilled with blue
precipitates appear after conjugation.