New crystal form of beta-lactoglobulin

The milk whey protein beta-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 Angstrom resolution, belong to the trigonal space group P3(1)21 with unit cell lengths a = b = 99.8 Angstrom, c = 67.7 Angstrom and unique angle gamma = 120.0 degrees. Although there have been many crystal forms reported for bovine beta-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 beta-lactoglobulin as the search model. The importance of the ovine structure in relation to that of the bovine is discussed.