Interactive modelling (MASSHA, SASpy) and global minimization programs (SASREF, BUNCH, CORAL, GLOBSYMM)
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Joined: 2014.10.22 21:21
Location: BioCAT, Advanced Photon Source


#1 Post by jbhopkins » 2014.10.22 21:38


I am investing a tetrameric protein complex made of four identical protein subunits. I have obtained a SAXS profile of the full complex, along with high resolution crystallographic data, and know that the symmetry in the crystal is P222, which matches well with what is observed in solution. Under certain conditions I believe the complex may partly dissociate, that is, there may be monomers, dimers, or trimers in solution along with the standard tetramer. I have scattering profiles under conditions where I believe this is happening (and they are different from the profile of the pure tetramer). I was hoping to use SASREFMX to model the dissociated components in solution.

However, there doesn't seem to be any manual available either online or in the sasdoc that comes with the atsas install. When I attempt to use sasrefmx, it needs a "file name with curves info (.con)" file. There's nothing like that in the standard sasref manual.

I would appreciate any help you can give me. I am also playing around with the online sasref, since I saw in another post in the forum that that had sasrefmx available, but I'm not sure what the right choices are (equilibrium mixture? what volume fractions to give, etc).


- Jesse

P.S. I know the right approach is to try to separate them out with inline SEC-SAXS, but that requires more beamtime, and I'd like to see if I can get at least some indication of what to expect before possibly attempting those experiments.

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#2 Post by anlarsen » 2018.01.23 01:02

The manual for SASREF MX: ... fcvmx.html

I can recommend running SASREF online, where you have the option to run SASREF MX, then the online version will generate the needed files, which you can use as templates for running it in offline batch mode.

Best regards,

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