Re: [ccp4bb] sulfur sad phasing

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

Previous message:
Subject: Re: SIRAS Phasing - SOLVE/RESOLVE
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2009-11-11

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Subject: Re: sulfur sad phasing
From: James Holton JMHolton {- at -} LBL {- dot -} GOV
Date: 2009-11-11

Subject: Re: sulfur sad phasing
From: Quyen Hoang qqhoang {- at -} GMAIL {- dot -} COM
Date: 2009-11-11

I played around with a few years back - tried all kinds of different
data collection strategies and wavelengths.
What worked for me was collecting data at wavelength of 1.7A from a
few different crystals and then merge them together to get a higher
redundancy.
Both calcium and sulfur signals were visible and provided enough
phasing power.

Bone recognition mechanism of porcine osteocalcin from crystal
structure.
Hoang QQ, Sicheri F, Howard AJ, Yang DS.
Nature. 2003 Oct 30;425(6961):977-80.

Radiation damage was a concern with longer wavelength.

Cheers,
Quyen

_______________________________
Quyen Hoang, Ph.D
Department of Biochemistry and Molecular Biology,
Start Neurosciences Research Institute
Indiana University School of Medicine
635 Barnhill Drive, Room MS0013D
Indianapolis, Indiana 46202-5122

Phone: 317-274-4371
Fax: 317-274-4686
email: qqhoang@iupui.edu

On Nov 11, 2009, at 10:23 AM, Jim Pflugrath wrote:

> 2.29 Angstrom is an excellent wavelength for Cl, Ca and S anomalous
> scatterers. This is the wavelength produced by a Cr home source.
> Some older references:
>
> Acta Crystallogr D Biol Crystallogr. 2003 Nov;59(Pt 11):1943-57.
> Epub 2003
> Oct 23. Away from the edge: SAD phasing from the sulfur anomalous
> signal
> measured in-house with chromium radiation.
>
> Acta Crystallogr D Biol Crystallogr. 2005 Jul;61(Pt 7):960-6. Epub
> 2005 Jun
> 24. Away from the edge II: in-house Se-SAS phasing with chromium
> radiation.
>
> Acta Crystallogr D Biol Crystallogr. 2005 Aug;61(Pt 8):1013-21. Epub
> 2005
> Jul 20. Structure determination of a novel protein by sulfur SAD using
> chromium radiation in combination with a new crystal-mounting method.
>
> I'm sure there are several structures done with Cr radiation since
> the above
> articles were published. Does any body else want to chime in?
>
> Jim
>
> -----Original Message-----
> From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of
> Matthias Zebisch
> Sent: Wednesday, November 11, 2009 6:16 AM
> To: CCP4BB@JISCMAIL.AC.UK
> Subject: [ccp4bb] sulfur sad phasing
>
> Dear bb!
>
> What is the optimal wavelength for Sulfur SAD phasing?
> Is it 1.9A or should one go below that to reduce absorption/damage.
>
> Also, would the same wavelength be appropriate to maximize anomalous
> scattering to position chlorides, calcium, sulfate in already phased
> structures?
>
> Thanks in advance,
>
> Matthias

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

Previous message:
Subject: Re: SIRAS Phasing - SOLVE/RESOLVE
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2009-11-11

Next message:
Subject: Re: sulfur sad phasing
From: James Holton JMHolton {- at -} LBL {- dot -} GOV
Date: 2009-11-11