Background: beta-Lactoglobulin is the major whey protein of cow and sheep's milk (~3 g/l), and is also present in many other mammalian species, a notable exception being humans. Bovine beta-lactoglobulin is a relatively small protein of 162 residues, with an 18.4 kDa molecular weight.In physiological conditions it is predominantly dimeric, but dissociates to a monomer below about pH 3. Nevertheless, its native state remains fairly intact at lower pH values, as determined using NMR. Synonyms: Beta-LG.