Riikka Reitzer wrote:
>> Hi there!
>> I am crystallizing a 130 kDa protein which crystalizes under variety of
> conditions and with different methods. Unfortenately the result is
> always more or less the same, twinned crystals. Sometimes I get nice
> looking ones, which look like single crystals. These often also turn out
> to be twinned or have high mosaicity.
>> So, now I am asking you people out there for tips, what would you do in
> my situation?
>
Crystals of moderately high mosaicity can be used for data collection.
In most cases 1. degree is OK, sometimes even 1.5-2.0 degree mosaic
crystals can be processed and give precise data.
Even twinned crystals can be used for diffraction studies. Twinning
is often generated by a 180. rotation, so similar reflections will
overlap systematically. It is bad for refinement, but good
for measuring differences, as they are subject to the same
systematic error. So MIR is not out of question for twinned crystals.
--
Zbyszek Otwinowski | zbyszek at chop.swmed.edu
University of Texas | tel : (214)-648-5098
Southwestern Medical Center | fax : (214)-648-5095
5323 Harry Hines Boulevard Dallas, Texas 75235-9038
[EOB]
