Anomalous Scattering

bill lodi at
Mon Jun 20 18:18:44 EST 1994

 In article <2tuen9INN13r5 at> vonrhein at (Clemens Vonrhein) writes:
 >Is there one reliable number/factor/... which will help me to judge if a
 >derivative dataset of my protein crystals has enough/sufficient anomalous
 >information to use it in SIRAS ? (e.g. anomalous patterson, phasing power,
 >FOM, how many percent of abs( F(+) - F(-) ) are above 3*SIGMA,...)
      Hopefully others can tell you which numbers they use for a guide;
I believe that so many factors influence protein data that the only really
useful guide is the quality of the SIRAS map, meaning can I see 
reasonably good (right-handed) helix at 3.5 A resolution.  Since one is
not dealing with the loopy merry-go-round of MIR refinements in the SIR
case, it should be not too difficult to make phases with and without the
anomalous data and compare maps.  My own blasphemous viewpoint is that 
anom. data taken from a reasonable derivative xtal on an area detector 
should not be tossed until proven to be useless.

Best of Luck

W. E. Meador

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