Crystallization and preliminary X-ray analysis of the vitamin D-binding protein from human serum.

The vitamin D-binding protein from human serum has been crystallized from polyethylene glycol as a complex with 25-hydroxyvitamin D3 and examined by X-ray diffraction photography. The space group of the crystals is C2 with a = 203.0 A, b = 75.8 A, c = 90.9 A and beta = 109.5 degrees. There are two molecules of 56,000 dalton in the asymmetric unit. The crystals diffract to about 3.0 A resolution but the patterns exhibit a substantial level of diffuse scatter.