SAS: A Converted Crystallographers' Experience

Bente Vestergaard
University of Copenhagen, Denmark

Macromolecular X-ray crystallography provides high-resolution structural information from proteins and other biomacromolecules. In spite of the very high relevance of this method, there are several structural features that are inherently difficult to study as a crystallographer. This is due to the fact that proteins should not be considered as "rock-steady" molecules. Rather, proteins adapt their structure as a response to stimulation which lies at the heart of the understanding of the structure:function relationship. Proteins form complexes with other macromolecules or small molecules (ligands, co-factors, lipids, substrates etc. etc.) and/or change conformation. They transiently interact, cluster, aggregate, breathe, unfold and refold and all of this often in an equilibrium between several structural species. I refer to this as "suprastructure" - i.e. structure at a higher level of complexity, than a single steady structure.

As a converted crystallographer, I will give examples of several studies where suprastructure has shown to be of high biological relevance, and how this can only be studied using SAS. Among other subjects, I will outline how we have used SAS to study the protein fibrillation processes for insulin and α-synuclein. Finally, I will tell about the bioXTAS project, where we develop a microfluidic sample environment which we will use for scanning the suprastructural space of proteins.

Vestergaard, B., Groenning, M., Roessle, M., Kastrup, J.S., van de Weert, M., Flink, J.M., Frokjaer, S., Gajhede, M., Svergun, D.I. (2007) A helical structural nucleus is the primary elongating unit of insulin amyloid fibrils. PLoS Biology 5(5), e134.

Toft, K.N., Vestergaard, B., Nielsen, S.S., Snakenborg, D., Jeppesen, M.G., Jacobsen, J.K., Arleth, L., Kutter, J.P. (2008) High-throughput Small Angle X-ray Scattering from Proteins in Solution using a micro-Fluidic Front-end. Analytical Chemistry 80, 3648-54.

Date/time: Saturday, 25 October, 9:45