Year: 2002
Type: article
Abstract: The radiation damage that results from high brilliance synchrotron beam lines severely limits the quality and quantity of information that can be measured from a single crystal.For small, marginally diffracting crystals the main issue is to find the minimal amount of experimental information that allows phasing, and also to use appropriate phase improvement methods to produce interpretable results.The synergism amongst experimental protocol, phasing methods, and scaling show the need to re-develop all of these methods simultaneously.Improvement of any one step generates an improvement in the final result, but due to the nonlinear nature of the problem the impact of improving all the steps together is larger than the sum of individual improvements.Radiation decay introduces substantial non-isomorphism that can be considered as the sum of consecutive changes.These include localized structural changes in a protein structure, rotations and translations of whole molecules in a crystal lattice and eventually total destruction of the protein tertiary structure.The localized structural changes introduce non-isomorphism that may be used as a source of phasing signal in a manner similar to the MIR method.So, an old enemy of the MIR method may be turned into a powerful phasing technique, assuming that the non-isomorphism introduced by radiation decay can be correctly modeled, at least within some reasonable accuracy.The newly developed scaling algorithms that exploit data redundancy allow for simultaneous correction of absorption, experimental system imperfections and radiation decay.The application of these algorithms resulted in the solution of new protein structures.
Authors: Z. Otwinowski, D. Borek, W. Minor
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2001094693