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Re: [ccp4bb] twin fraction varies between crystals?
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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: twin fraction varies between crystals?
From: Dirk Kostrewa dirk {- dot -} kostrewa {- at -} PSI {- dot -} CH
Date: 2007-04-18		Next message:
Subject: Re: twin fraction varies between crystals?
From: Ian Tickle I {- dot -} Tickle {- at -} ASTEX-THERAPEUTICS {- dot -} COM
Date: 2007-04-18


Subject: Re: twin fraction varies between crystals?
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-04-18

This is a very common thing - twinning is a sort of accidental overlap
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 navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: twin fraction varies between crystals?
From: Dirk Kostrewa dirk {- dot -} kostrewa {- at -} PSI {- dot -} CH
Date: 2007-04-18		Next message:
Subject: Re: twin fraction varies between crystals?
From: Ian Tickle I {- dot -} Tickle {- at -} ASTEX-THERAPEUTICS {- dot -} COM
Date: 2007-04-18
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