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Re: [ccp4bb] twin fraction varies between crystals? |
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CCP4bb navigationCCP4bb <-- 2007 <-- April 2007 <-- 18 April 2007Subject: Re: twin fraction varies between crystals? From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK Date: 2007-04-18 of crystal fragments and thus will be different for diferent "crystals". ( Should a twinned object be called a crystal? Discuss) More serious - it is probably different for different parts of the data collection if your crystal is smaller than the beam - I dont know if anyone has ever tried to analyse for this. In our experience smaller is often better.. Eleanor Mark Mayer wrote: > For cases where people have had merohedral twinning, did the twin fraction vary substantially > between individual crystals grown under indentical conditions? I have no prior experience with > merohedral twinning, and was surprised to see that the twin fraction varied substantially as detailed > below, and that by screening we were able to get untwinned xtals. > > The project started with a weak home data set for which the twin fraction was 0.478, and which > scaled in both H3 and H32. We just came back from APS with data sets from another three crystals, > for which the ML twin fraction, estimated using phenix.xtriage with scalepack merged intensities as > input, varied from 0.335, 0.219 and 0.02. The latter is refining very nicely, in H3 and will not scale in > H32. > > Thanks - Mark > > > > CCP4bb navigationCCP4bb <-- 2007 <-- April 2007 <-- 18 April 2007 |
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