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Industrial Liaison Group:
Tel: +44 (0) 1235 778797
E-mail: [email protected]
Welcome to day 12 of the Diamond Industrial Liaison advent calendar and happy Monday to you all. Today we are going to give you an oversight of BioSAXS, another of the techniques available to researchers here at Diamond.
Solution small angle X-ray scattering (also known as protein SAXS or bioSAXS is a powerful tool for analysis of the structure of proteins in solution. Although care must be taken to ensure that the samples are pure and free from aggregation in advance of the measurement (as this is assumed for data analysis and cannot be measured directly), it can be used for a wide range of protein types and solution conditions.
The resolution of SAXS is about 15 Å.
Key advantages of protein SAXS include:
• Determination of protein molecular weight.
• Structure validation. X-ray crystallography is the dominant method of structure determination, however because of the nature of crystal packing, the solution structure or oligomeric state may not be clear and may be ascertained using bioSAXS. Protein SAXS has also been used in conjunction with NMR to give more accurate structure determination of large proteins. While it is difficult to prove a model is correct with small angle scattering, it is possible to show that a proposed model is incorrect or incomplete.
• Characterisation of multi-domain proteins. Ab initio shape restoration is now possible using modern algorithms and large scale computing resources to provide information about the overall space envelope. When additional information is available, for example a crystallographic structure, for a subcomponent(s) of a modular protein or complex, it is possible to use a combination of ab initio shape restoration and rigid body refinement to model the structure of the protein.
• Modelling multi-subunit complexes. When significant conformation changes are associated with ligand binding, it is possible to monitor these changes in overall shape of the protein in the presence and absence of a ligand using SAXS.
• Flexible proteins. Protein SAXS data represent an average of all structures present in the solution throughout the measurement time. As such, it is possible to investigate the average solution structure of flexible proteins.
BioSAXS for Flexible Proteins
BioSAXS for Macromolecular Complexes
BioSAXS for Ligand Binding
BioSAXS for Particulate Suspensions
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