Speaker: Ralf Biehl, Jülich Centre for Neutron Science (JCNS), Germany.

The Antibodies in Solution: a LINXS – NIST Webinar Series provides background information related to the currently ongoing LINXS antibody research program. This is a concerted experimental and theoretical effort that aims to investigate the properties of monoclonal antibodies in solution, which comprise a major platform for potential drug candidates and are of high academic and pharmaceutical interest. An international consortium of researchers at academic institutions, research centers, NIST and Novartis has teamed up for this. Didactical lectures given by members of the consortium on different experimental and theoretical topics that are highly relevant for state-of-the-art antibody research as well as insights from pharmaceutical industry will be broadcasted. A central aspect of the webinar series will be to illustrate the full power of neutron and X-ray scattering science that can be achieved in combination with complementary experimental methods and different unifying simulation techniques.

Abstract:

The biological function of proteins is often related to configurational changes and large-scale domain motions, which are induced or suppressed by the binding of a substrate or due to cosolvents. Domain motions can be related to soft hinges, flexible linker regions or -as in the case of intrinsically disordered proteins- be native to proteins without secondary or tertiary structure. These large-scale domain motions in solution cannot be observed by X-ray crystallography or NMR spectroscopy. Small angle scattering (SAS) by X-rays or neutrons in combination with neutron spin echo spectroscopy (NSE) in solution can be used to observe configurational changes and equilibrium dynamics between functional domains on 1-300 nanosecond timescale.

I will present examples for different types of motions related to the structure of proteins and bioconjugates. Thermal unfolded Ribonuclease A shows polymer like dynamics despite the 4 disulfide bonds restricting the degrees of freedom. Prior to full unfolding the protein unfolding dynamics is observed. Polyelectrolytes have structural and dynamical similarities with IDP. The domain protein Phosphoglycerate kinase shows a hinge motion between the main domains related to function. PEGylation seems not to influence this domain motion but adds additional internal dynamics in the protein-polymer complex. Antibodies present a strong dynamics due to the short linkers connecting the Fc with the Fab domains. The observed dynamics is related to internal forces, solvent friction and the role of charge screening.