replicate SAXS measurements

Plan your small angle X-ray or neutron scattering measurements
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ZachMaben
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Joined: 2018.01.24 05:34

replicate SAXS measurements

#1 Post by ZachMaben » 2018.01.24 06:05

Hello, I am a graduate student who is trying to introduce SAXS to my laboratory. I have collected some data and processed it using the techniques I found on this forum. My project involves measuring a large conformational change in my protein of interest, which causes a slight change (0.5-2 angstroms) in Rg and a more notable change at 0.15 < q < 0.2 angstrom-1.

My mentor often asks about the reproducibility of the data, and inquires about replicate measurements of the same sample, such as would often be done in biology. I have the impression that this is not commonly done in SAXS experiments, but I do not know how to explain this to my mentor. It is hard to argue that more data is bad, even if it may be impractical.

I would appreciate any guidance on this topic. I have not found publications that discuss this topic but welcome any and all referrals. Thank you for your help.

mawhite
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Joined: 2011.08.15 22:18
Location: UTMB, Galveston, TX

Re: replicate SAXS measurements

#2 Post by mawhite » 2018.01.31 23:55

Zach,

In the simplest sense the standard dilution series is a replicate set, which demonstrates the reproducibility and concentration independence of your data. However, it does not account for sample preparation variation. Contaminants and buffer mismatch problems should vary between sample batches, which is a good reason to collect SAXS on more that one sample prep, but this is rarely done, unless the first prep shows sample pathologies in the SAXS data.

Best regards,
Mark

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