The integration of SEC-SAXS
One of the major problems faced during BioSAXS experiments is the monodispersity of the target protein. Even tiny amounts of impurities or protein aggregation caused from transport of sample can dramatically affect the quality of the scattering curves. The development of a high-performance liquid chromatography (HPLC) sample environment for solution scattering (SEC-SAXS) that couples the use of established biological separation techniques to the scattering experiment itself have helped resolve this issue. Mark is currently upgrading the SEC-SAXS on B21 to a standard that should enable high throughput of samples both in terms of sampling and software.
The glycans present on the surface of proteins can vary greatly in size from being very minor in amount to being the dominant factor. There functions too are very diverse from structural scaffolding to signalling through glycan binding proteins. Mark is studying the relationship between the glycan and protein, utilising SAXS to determine the volumes of each glycan, and their spatial characteristics when bound to the protein.
Heparin binding proteins
Fibroblast growth factors (FGFs) are a well-known family of proto-typical Heparan Sulphate (HS)/heparin binding proteins. They are the extracellular component of the fibroblast growth factor receptor (FGFR) cell signalling system. Mark is studying the binding of heparin to FGF’s with the native glycosylated form and the ‘nude’ variants to elucidate any relationship between the heparin binding and glycosylation.
Radiation damage in SAXS
Protein degradation through radiation damage is a common problem associated with SAXS beamlines. The main causative agent for this damage is thought to be the hydroxyl radical formed from the breakdown of water by the X-rays. Mark is investigating using different compounds to both limit the effects and to test whether the hydroxyl radical is the causative agent or not.