Obscurin Ig57/58 ---------------- These data were collected at Argonne National labs on obscurin Ig57/58, and were published in a 2019 Protein Science article (Whitley *et al.*). These data are on 2 Ig domains attached together with a flexible linker (pdb: 6MG9 for the first domain, 2MWC for the second domain; sequence 4248-4430 of accession number CAC44768.1). Thus, this protein fragment is flexible, and thus cannot be treated as a rigid body. As a first approximation of the size, analyze the Guinier plot. A [gnom/ATSAS][1] analysis is will only be of limited use, due to flexibility. To really get at the flexibility issue, we recommend taking the data and either using [SASSIE][2] or [MultiFOXS][3], both of which are free online servers. Our tutorials of how to handle and analyze these data are in the 'SAXS Tutorial' files tab. [1]: https://www.embl-hamburg.de/biosaxs/software.html [2]: http://www.smallangles.net/sassie/SASSIE_HOME.html [3]: https://modbase.compbio.ucsf.edu/multifoxs/