Hemocyanin, Keyhole Limpet is used to immunize animals to elicit antibodies to small molecules (haptens) by covalent conjugation. It is often used as a carrier protein due to its highly immunogenic properties and the large number of lysine residues available for modification. Soluble KLH is suitable for the preparation of immunogens for injection, or as a control protein for ELISA and dot blot immunoassay due to its high solubility in water and buffers.