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OVA

Ovalbumin is the main protein found in egg white, making up 60-65% of the total protein. Ovalbumin displays sequence and three-dimensional homology to the serpin superfamily, but unlike most serpins it is not a serine protease inhibitor. The function of ovalbumin is unknown, although it is presumed to be a storage protein.

The ovalbumin protein of chickens is made up of 385 amino acids, and its relative molecular mass is 45 kDa. It is a glycoprotein with 4 sites of glycosylation. It is secreted from the cell. Unlike the signal sequences of most secreted proteins, Ovalbumins signal sequence is not cleaved. Additionally it is not located directly on the N-terminus, but rather internally, starting at residue 21 and ending at residue 47.

KLH

Keyhole limpet hemocyanin (KLH) is an extremely large, heterogeneous glycosylated protein consisting of subunits with a molecular weight of 350,000 and 390,000 in aggregates with molecular weights of 4,500,000-13,000,000. multisubunit, oxygen-carrying, metalloprotein found in the hemolymph of the giant keyhole limpet, Megathura crenulata, that lives off the coast of California from Monterey Bay to Isla Asuncion off Baja California.

Keyhole limpet hemocyanin (KLH) is used extensively as a carrier protein in the production of antibodies for research, biotechnology and therapeutic applications. Haptens are substances with a low molecular weight such as peptides, small proteins and drug molecules that are generally not immunogenic and require the aid of a carrier protein to stimulate a response from the immune system in the form of antibody production.[3] KLH is the most widely employed carrier proteins for this purpose. KLH is an effective carrier protein for several reasons. Its large size and numerous epitopes generate a substantial immune response, and abundance of lysine residues for coupling haptens, allows a high hapten:carrier protein ratio increasing the likelihood of generating hapten-specific antibodies. In addition, because KLH is derived from the limpet, a gastropod, it is phylogenetically distant from mammalian proteins, thus reducing false positives in immunologically based research techniques in mammalian model organisms.

BSA

Bovine serum albumin (BSA) is one of the most commonly used carriers for conjugation in antibody production. It belongs to the class of serum proteins called albumins, which make up about half of the protein in plasma and are the most stable and soluble proteins in plasma. It is very popular with laboratories developing immunoassays, mostly due to its availability, solubility and the numerous functional groups present for coupling to heptans.

    Molecular weight (MW): The MW of BSA is 67 X 103 which is much smaller than that of KLH, another commonly used carrier protein. It is, however, much more soluble and is immunogenic. It contains 59 lysines, and 30-35 of these are primary amines capable of reacting with a conjugation sites of linkers. It is a popular carrier for weakly antigenic compounds.

Solubility in aqueous solution: BSA is easily dissolved in an aqueous solution. It can be highly purified to become homogeneous. BSA is commonly used as protein standard in protein assays and as a molecular weight standard for SDS-PAGE and gel permeation chromatography.

 BSA can be used to block nonspecific binding sites in many immunochemical experiments such as ELISA, immunoblotting and immunohistochemical studies. It may be used as a non-relevant protein in enzyme immunoassays KLH cannot be used for this because the anti-KLH antibodies, which formed during immunization, will interfere with the measurement of anti-heptan antibodies. When KLH is used as the carrier, heptan-BSA conjugates can be used because they do not interfere with the measurement for anti-heptan antibodies.