Re: [ccp4bb] Strange diffraction images

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

Previous message:
Subject: Re: alternating strong/weak intensities in reciprocal planes - P622
From: Dale Tronrud det102 {- at -} UOXRAY {- dot -} UOREGON {- dot -} EDU
Date: 2007-08-27

Next message:
Subject: Re: Strange diffraction images
From: Jacob Keller j-keller2 {- at -} MD {- dot -} NORTHWESTERN {- dot -} EDU
Date: 2007-08-27

Subject: Re: Strange diffraction images
From: Bart Hazes bart {- dot -} hazes {- at -} UALBERTA {- dot -} CA
Date: 2007-08-27

I believe Wayne Hendrickson's lab has had such a case with a 10-fold
symmetric mollusc hemocyanin crystal. This must have been in the early
90's and to my knowlwedge they were never able to solve the structure
even though it diffracted beyond 2 Anstrom.

I'm not sure if this work has been published but you can check the paper
describing a single domain of this protein complex or contact one of its
authors.

Bart

J Mol Biol. 1998 May 15;278(4):855-70.

Crystal structure of a functional unit from Octopus hemocyanin.
Cuff ME, Miller KI, van Holde KE, Hendrickson WA.

Jacob Keller wrote:
> I am still eagerly awaiting a biomacromolecular quasicrystal with a five-fold symmetric diffraction
> pattern. It seems that this is entirely possible, if one gets roughly Penrose-tile shaped oligomers
> somehow. But wow, how would you solve that thing? I guess one would have to modify software from
> the small molecule or matsci folks.
>
> Jacob
>
>
> ==============Original message text===============
> On Mon, 27 Aug 2007 11:19:15 am CDT "George M. Sheldrick" wrote:
>
>
> Some small molecule crystallographers have specialized in solving and
> refining structures that, exactly as you describe it, consist of two (or
> more) interpenetrating, non-commensurable lattices. The usual approach is
> to decribe the crystal in up to six dimensional space. The programs SAINT
> and EVALCCD are able to integrate such diffraction patterns and
> SADABS is able to scale them. However the case in point is probably
> commensurate.
>
> George
>
> Prof. George M. Sheldrick FRS
> Dept. Structural Chemistry,
> University of Goettingen,
> Tammannstr. 4,
> D37077 Goettingen, Germany
> Tel. +49-551-39-3021 or -3068
> Fax. +49-551-39-2582
>
>
> On Mon, 27 Aug 2007, Jacob Keller wrote:
>
>
>>What a beautiful and interesting diffraction pattern!
>>
>>To me, it seems that there is a blurred set of spots with different cell dimensions, although
>>nearly the same, underlying the ordered diffraction pattern. A possible interpretation occurred to
>>me, that the ordered part of the crystal is supported by a less-ordered lattice of slightly
>>different dimensions, which, because the crystal is a like a layer-cake of 2-d crystals, need not
>>be commensurable in the short range with the ordered lattice. The nicely-ordered "cake" part of the
>>crystal you solved, but the "frosting" between is of a different, less ordered nature, giving rise
>>to the diffuse pattern which has slightly different lattice spacing. I would have to see more
>>images to know whether this apparent lattice-spacing phenomenon is consistent, but it at least
>>seems that way to me from the images you put on the web. I would shudder to think of indexing it,
>>however.
>>
>>All the best,
>>
>>Jacob Keller
>>
>>ps I wonder whether a crystal was ever solved which had two interpenetrating, non-commensurable
>>lattices in it. That would be pretty fantastic.
>
>
>
> Jacob,
>
> Some small molecule crystallographers have specialized in solving and
> refining structures that, exactly as you describe it, consist of two
> interpenetrating, non-commensurate lattices. The usual approach is
> to index the diffraction pattern in multiple dimensional space
> ('superspace'). The programs SAINT and EVALCCD are able to integrate
> diffraction patterns in up to six dimensions, SADABS is able to scale
> them and the refinement is almost always performed with Petricek's
> program JANA2000:
>
> http://www-xray.fzu.cz/jana/Jana2000/jana.html
> However the case in point is probably commensurate.
>
> George
>
> Prof. George M. Sheldrick FRS
> Dept. Structural Chemistry,
> University of Goettingen,
> Tammannstr. 4,
> D37077 Goettingen, Germany
> Tel. +49-551-39-3021 or -3068
> Fax. +49-551-39-2582
> ===========End of original message text===========
>
>
>
> ***********************************
> Jacob Keller
> Northwestern University
> 6541 N. Francisco #3
> Chicago IL 60645
> (847)467-4049
> j-keller2@northwestern.edu
> ***********************************
>
>

--

==============================================================================

Bart Hazes (Assistant Professor)
Dept. of Medical Microbiology & Immunology
University of Alberta
1-15 Medical Sciences Building
Edmonton, Alberta
Canada, T6G 2H7
phone: 1-780-492-0042
fax: 1-780-492-7521

==============================================================================

CCP4bb navigation

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

Previous message:
Subject: Re: alternating strong/weak intensities in reciprocal planes - P622
From: Dale Tronrud det102 {- at -} UOXRAY {- dot -} UOREGON {- dot -} EDU
Date: 2007-08-27

Next message:
Subject: Re: Strange diffraction images
From: Jacob Keller j-keller2 {- at -} MD {- dot -} NORTHWESTERN {- dot -} EDU
Date: 2007-08-27