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BP: Fachverband Biologische Physik

BP 24: Posters - Protein Structure and Dynamics

BP 24.3: Poster

Dienstag, 21. März 2017, 14:00–16:00, P1A

Characterization of open and closed beta 2 glycoprotein I conformation — •Ina Buchholz, Peter Nestler, Florian Berg, and Mihaela Delcea — University of Greifswald, ZIK HIKE, Fleischmannstr. 42, 17498 Greifswald, Germany

The antiphospholipid syndrome (APS) is an autoimmune disease characterized by the presence of anti-beta 2 glycoprotein I (b2GPI) antibodies circulating in blood of patients. b2GPI exists in at least two different conformations: the closed form which is found circulating in blood and the open form which exposes a cryptic binding site (i.e. epitope). This antigenic conformation leads to formation of antibody-protein complexes which induce thrombotic events and recurring pregnancy loss. To identify the conditions that direct to the development of APS, a conversion protocol is used to prepare the open and closed forms of b2GPI. Therefore, the structures of b2GPI are studied by circular dichroism spectroscopy, fluorescence spectroscopy and atomic force microscopy in varying buffer systems. First results indicate inherent differences between open and closed conformation. Some experimental conditions also provide mixed conformational populations. These findings will be handled as a basic reference for further experiments aiming for the alteration of b2GPI protein structure. For this, the influence of different stress conditions like pH shift, temperature change or ionic strength, as well as the binding of various ligands to b2GPI will be investigated and will be further correlated with APS antibody binding to b2GPI.