Re: [ccp4bb] bond lengths, angles, ideality and refinements

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

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Subject: Re: Sulfate ion on 2-fold axis
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2008-01-10

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From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2008-01-10

Subject: Re: bond lengths, angles, ideality and refinements
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2008-01-10

Am 09.01.2008 um 20:48 schrieb Anastassis Perrakis:

> I actually think that inaccurate cells are a big source of misery
> in many refinements. I have found the idea
> of WhatCheck to actually check your cell by looking at the
> projection of bond lengths of certain types along the cell axes
> most useful.
> I would hardly advocate to measure your cell that way, but going
> back to you data and looking at the cell again would be worth it.

There was a discussion many years ago on this bulletin board about
unit cell scaling errors reported by WHAT_CHECK that resulted merely
from some different dictionary values used in the refinement program
(CNS, if I remember correctly) and in WHAT_CHECK, although both
claimed to use the Engh & Huber parameters. This difference projected
onto the unit cell axes resulted in a reported unit cell scaling
error, that could not be fixed by iterative rescaling of the unit
cell and refinement, and thus was an artifact. So, I wouldn't even
trust the unit cells reported by WHAT_CHECK . . .

Best regards,

Dirk.

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Dirk Kostrewa
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CCP4bb navigation

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

Previous message:
Subject: Re: Sulfate ion on 2-fold axis
From: Eleanor Dodson ccp4 {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2008-01-10

Next message:
Subject: Re: unbiased electron density map
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2008-01-10