title: Studies on the essential intramolecular interaction between the A1 and A2 domains of von Willebrand factor.
abstract: Haemostasis depends on the balanced participation of von Willebrand factor (vWF), a large multimeric and multidomain glycoprotein with essential role during the initial steps of blood clotting. Mature vWF circulates in plasma with the form of multimers comprised of several domains with diverse functions. More specifically, the A1 domain of vWF plays crucial role in haemostasis, regulating the mechanism of platelet adhesion in sites of vascular injury while A2 domain regulates the normal turnover of vWF. Recent studies have implied that an intramolecular interaction between A1 and A2 domains exists, which prevents platelets adhesion and subsequently inhibits the initial step of the blood coagulation mechanism. In an effort to elucidate the essential nature of the interaction between these two domains, we produced and purified the corresponding recombinant unmodified polypeptides. The secondary structure of the two domains was studied individually and as a mixture using circular dichroism spectroscopy. The observed interaction was verified by ELISA competition assays using antibodies and their ability to form productive interactions was further characterized kinetically. In silico analysis (docking and molecular dynamics simulations) of the A1-A2 binding indicated three possible structural models highlighting the crucial, for this interaction, region.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 41221 Larissa, Greece.
authors.forename: Zoi
authors.initials: Z
authors.lastname: Karoulia
authors.forename: Georgios
authors.initials: G
authors.lastname: Papadopoulos
authors.forename: Michail
authors.initials: M
authors.lastname: Nomikos
authors.forename: Angelos
authors.initials: A
authors.lastname: Thanassoulas
authors.forename: Theodora Choli
authors.initials: TC
authors.lastname: Papadopoulou
authors.forename: George
authors.initials: G
authors.lastname: Nounesis
authors.forename: Maria
authors.initials: M
authors.lastname: Kontou
authors.forename: Constantinos
authors.initials: C
authors.lastname: Stathopoulos
authors.forename: Demetres D
authors.initials: DD
authors.lastname: Leonidas
mesh_terms: D002478:Cells, Cultured; D002942:Circular Dichroism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D011487:Protein Conformation; D014841:von Willebrand Factor / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor