Dear All, I am currently attempting to phase a protein domain target after soaking the crystal with Tobias Beck's I3C magic crystal compound, using XDS and SHELX. After XDS processing, I was able to detect 27% anomalous signal. I used ccp4 to generate an .mtz file. After attempting to convert the .mtz file to .sca, using mtz2sca and mtz2various (on ccp4), and running into the same problem (below), I used XDSCONV to generate a SHELX .hkl file.
Inputting both a native .hkl file and anomalous .hkl file into SIRAS (suggested to be the best for an iodide soak) through SHELXC/D/E gave a pseudoCC of 51% (using -m200 in SHELXE). However, looking at the output .lst file from SHELXD indicates that of about 32000 reflections, over 13000 were rejected. If there something specific to prevent half of my reflections from being rejected in SHELX? I'm hoping that with them included, my CC value will be higher (closer to the recommended 70% for a probable solution, although in certain documents it says only 30% is needed for SAD phasing?). I have been using HKLF 3 (F values), should I be using HKLF 4 (F SQUARED values)? Should I use the SAD SHELXC program, instead of SIRAS (when trying this, the SAD program was unable to recognize my XDSCONV output .hkl file)? Is .sca a better input file? Can I process the data in XDS initially to gear toward phase determination in SHELX? Thanks! Jeanine
ja027_shelx_fa.lst
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