Crystallization and preliminary x-ray studies of flavocetin-A, a platelet glycoprotein Ib-binding protein from the habu snake venom.

Flavocetin-A (FL-A) is a platelet glycoprotein Ib-binding protein, a high molecular mass oligomer (149 kDa) of C-type lectin-like subunits alpha and beta isolated from the habu snake venom. Purified FL-A crystallized in the tetragonal space group I4 with unit-cell dimensions a = b = 121.0, c = 63.2 A. The crystals diffract to at least 2.4 A resolution. The structure has been solved by molecular replacement using the crystal structure of factors IX/X-binding protein (PDB code 1ixx) as a search model. The asymmetric unit contains one heterodimer, showing that FL-A is a novel tetradimer (alphabeta)(4) composed of four heterodimers related by a crystallographic fourfold axis.