Haptoglobin is a serum protein that consists of two alpha and two beta chains connected by disulfide bridges. The alpha and beta chains are characterized by molecular weights of ~10 kDa and ~40 kDa respectively. It acts as a hemoglobin scavenger and has been associated with protease inhibitory activity. It is a positive acute phase reactant, the levels of which increase significantly in cats in response to inflammation, tissue injury or disease. Haptoglobin is purified using a combination of affinity and gel filtration chromatography steps.