New crystal form of β-lactoglobulin

The milk whey protein β-lactoglobulin has been isolated from ovine milk, purified and crystallized in a form suitable for X-ray crystallography. The crystals, which diffract to 1.9 A resolution, belong to the trigonal space group P3 1 21 with unit cell lengths a = b = 99.8 A, c = 67.7 A and unique angle γ = 120.0°. Although there have been many crystal forms reported for bovine β-lactoglobulin, none has been reported with these unit cell parameters. A preliminary native data set has been collected and a molecular replacement solution obtained, using the structure of dimeric bovine β-lactoglobulin as the search model. The importance of the ovine structure in relation to that of the bovine is discussed.