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Biologische Systeme und Medizin Poster: Mi., 14:00–16:30 M-P211
Towards automated BioXAS
Gerd Wellenreuther 1 , Wolfram Meyer-Klaucke 1
1 EMBL Outstation Hamburg, Notkestr. 85, 22603 Hamburg
Automation of XAS data reduction and analysis is essential to cope with high-throughput
data collection becoming available at an increasing number of synchrotron radiation
centers. Recently, a flexible script called Kemp has been developed and introduced
at the XAS beamline at EMBL Hamburg. It automatically processes fluorescence
XAS data. The pipeline includes dead time correction, energy calibration, selection of
fluorescence detector channels as well as the extraction of XANES and EXAFS [1].
In a second step, we introduced an universal algorithm for automated BioXAS data
analysis. Only the EXAFS data and a range of possible coordinations and ligands (e. g.
coordination number ranging from 3-6 and potential ligands being sulfur, nitrogen, oxygen
or histidine) have to be provided. All permutations are fitted to the experimental
data; the individual refinements are performed by DL EXCURV [2]. Models leading
to unreasonable fit parameters are rejected based on a comparison with an internal
database. In the next step, the most favorable structure is identified by the goodnessof-fit
parameter. The results are summarized in a HTML-file containing all structural
models as well as plots of the best fits.
The entire process requires few seconds to minutes using single-scattering approximation
and considerably longer when the multiple scattering algorithm is included.
Initially, the program mainly provides assistance for the scientist analyzing BioXAS
data. This will change once that the algorithm is implemented on a computer cluster
allowing multiple-scattering analyses within minutes and the identification of standard
metal binding motifs. On the long run this might open the door towards an online
structure determination during an experiment.
[1] Korbas, M., Fulla Marsa, D., and Meyer-Klaucke, W., submitted
[2] S. Tomic et al, CCLRC Technical Report DL-TR-2005-001, ISSN 1362-0207(2005)