Dear Li,
In regards to concentration ideally you should do a concentration series
and from that perform a zero concentration extrapolation. Typically we've
had success with a 1-10 mg/ml series and 1.5-3 s exposures at SSRL but
it's going to be dependent on molecular weight. You should monitor your
signal to look for any up turn at low resolution that would indicate
multi-particle interaction or aggregation. If you have signal in the lower
concentration samples and you see this effect in the higher concentration
ones then take the sequence to more dilute ones. Advice from the beamline
scientist or instrument manufacturer should guide you on typical
concentrations and exposure times for the source you plan to use.
We found the review by Putnam, Hammel, Hura, and Tainer entitled "Solution
scattering (SAXS) combined with crystallography and computation: defining
accurate macromolecular structures, conformations and assemblies in
solution" (Q Rev Biophys. 2007 Aug;40(3):191-285) to be very useful for
practical information. This is available at
http://bl1231.als.lbl.gov/publications/index.php. There is also a good
example of what to expect in your data at
http://bl1231.als.lbl.gov/saxs_protocols/saxs_data_collection_evaluatio.php
which is also in the paper.
Cheers,
Eddie
Edward Snell Ph.D.
Assistant Prof. Department of Structural Biology, SUNY Buffalo,
Hauptman-Woodward Medical Research Institute
700 Ellicott Street, Buffalo, NY 14203-1102
Phone: (716) 898 8631 Fax: (716) 898 8660
Email: [log in to unmask] Telepathy: 42.2 GHz
Heisenberg was probably here!
> Dear Li,
>
> The SIBYLS Beamline web page has useful sample prep information at
> http://bl1231.als.lbl.gov/saxs_protocols/index.php. They also have a link
> to a very good SAXS review article.
>
> Cheers,
> Angela
>
>
>
>
> Li Sheng <[log in to unmask]>
> Sent by: CCP4 bulletin board <[log in to unmask]>
> 04/23/2009 06:19 AM
> Please respond to
> Li Sheng <[log in to unmask]>
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> [ccp4bb] protein purity in SAXS
>
>
>
>
>
>
> Dear all,
>
> Is there anyone with experience in small angle x-ray scattering? Could
> anyone please tell me the requirements for protein sample purity and
> concentration?
> Thanx in advance.
>
>
>
> Sincerely,
> Li
>
> __________________________________________
> Email:[log in to unmask]
> Institute of Biochemistry and Cell Biology
> Institutes for Biological Sciences
> Chinese Academy of Sciences
> 320 Yue-Yang Road, Shanghai 200031, China
> Tel: +86-21-5492-1217
> __________________________________________
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>
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