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| Peter Timmins - SANS: Contrast Variation and Specific Deuteration | |
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Peter Timmins
ILL, Grenoble, France
The negative scattering length of hydrogen compared with the rather similar, positive, scattering length of its heavy isotope deuterium and the other atoms comprising biological macromolecules is at the origin of almost all applications of SANS to biological systems. The simplest application is in the variation of contrast by substitution of heavy water for light water. In this way different chemical components of a macromolecular complex, such as proteins, nucleic acids or lipids can be highlighted. In the case of multi-protein complexes, where all components have the same contrast, single proteins can be visualized by specific deuteration.
The application of the contrast variation approach can be at the very simple model independent level, based simply on radius of gyration arguments: this allows intermolecular distances to be calculated and relative positions of sub-units with respect to centre of mass. On the other hand molecular modeling, for example by dummy atoms, can be enhanced by the existence of several different scattering curves from the same complex but with different components highlighted.
A short explanation of deuteration methods and applications of contrast variation will be described.
Date/time: Sunday, 29 October, 9:45
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