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: "Bryan W {- dot -} Lepore" bryanlepore {- at -} MAIL {- dot -} UTEXAS {- dot -} EDU
Date: 2007-04-17

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

Subject: Re: twin fraction varies between crystals?
From: Dirk Kostrewa dirk {- dot -} kostrewa {- at -} PSI {- dot -} CH
Date: 2007-04-18

Hi Mark,

thus far, in the many cases where we had merohedral twinning, the twin
fraction varied usually a lot, ranging from ~0.1-0.5 for the same
crystallization conditions. So, it's a good idea to screen a couple of
crystals and check their twin fractions (estimating the true twin
fraction is a completely different story ...).

Good luck,

Dirk.

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

--

****************************************
Dirk Kostrewa
Paul Scherrer Institut
Biomolecular Research, OFLC/110
CH-5232 Villigen PSI, Switzerland
Phone: +41-56-310-4722
Fax: +41-56-310-5288
E-mail: dirk.kostrewa@psi.ch
http://sb.web.psi.ch
****************************************

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: twin fraction varies between crystals?
From: "Bryan W {- dot -} Lepore" bryanlepore {- at -} MAIL {- dot -} UTEXAS {- dot -} EDU
Date: 2007-04-17

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