HEMOCYANIN, KEYHOLE LIMPET

Hemocyanin from Limulus polyphemus hemolymph has been used:

• in electrophoretic field gradient focusing as a reference standard for optimizing fluorescence quenching for noncolored proteins
• as standard protein for pH based crystallization screening experiments
• in peptide conjugation studies

Keyhole limpet hemocyanin (KLH) is a strong and well known immune-stimulant in both experimental animals and humans. It has been used as a hapten carrier protein to enhance antigen-specific T cell priming and is known to stimulate a CD4⁺ T-cell response.
Hemocyanin was used to study if antipeptide antibodies specifically recognize the l1 protein of the human papilloma virus of type 31. It was also used to study the acid-induced unfolding of didecameric keyhole limpet hemocyanin.

Gastropod hemocyanins are massive glycoproteins (4 to 8 MDa) designed by an intricate arrangement of 10 subunits that are self-assembled into hollow cylinders 35 nm in diameter.

The largest hemocyanin molecules consisting of 48 (8 × 6) subunits are present in horseshoe crabs (Limulus polyphemus) have up to eight distinct subunits type (6 × subunit type I, 8 × II, 2 × IIA, 8 × IIIA, 8 × IIIB, 8 × IV, 4 × V, 4 × VI).