HP(Haptoglobin) is also named as zonulin and belongs to the peptidase S1 family. HP, a plasma glycoprotein that binds free hemoglobin, has a tetrameric structure of 2 alpha(16 kDa and 9 kDa) and 2 beta(40 kDa) polypeptides that are covalently associated by disulfide bonds. In most species, apart from ruminants, Hp has a molecular mass of 100 kDa, consisting of two subunits of 40 kDa and two subunits of 9 kDa, although in a few species, such as man, genetic variant of Hp forms polymers of higher mass(PMID:2361363). Recent studies of haptoglobin show that certain oligosaccharide structures predominate in different diseases. For example, a highly-fucosylated structure is found in breast cancer and ovarian cancer, highly-sialylated structures in Crohn's disease and highly branched structures in alcoholic liver disease and fucosylated haptoglobin is a good serum marker for pancreatic cancer.(PMID:16385567).