Dear Marie, I believe that the first of Fred's explanations can mostly be corrected for by scaling (and it could partly be overcome by longer exposure times as long as radiation damage does not kick in).
In your case, where one cell axis is about 10x as long as the other two, Fred's second explanation is probably the real cause of anisotropy: the unit cells would have to be in proper order in the c-direction over 10x the range compared to a/b in order to reach the same resolution. Tim On Wed, Jun 09, 2010 at 12:22:59PM +0000, Marie Lacroix wrote: > > > > > Hi, > > I also have a question concerning anisotropic data. Collected a data set and > the best crystal gave highly anisotropic diffraction patterns ( 3.7 A - 5.8 > A). So my first question is how to handle these data. I got only experience > with "normal data" using the ccp4 suite. Are there any program specially for > these kind of data? There are? > The second question is how anisotropic data occur? The protein I work with > has a tetragonal sg with a=b= 86.0 and an extremely long c axis of 651 A. > Secondary Structure prediction suggest a lot of beta strands. How can I > explain the anisotropy (for my own interest and my thesis)? > Thank you very much. > > Marie > > -- -- Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A
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