Attenuate the beam massively, and/or speed up the frame rate. Also mount the flying saucers to enable shooting from the side--use a bent micromesh. Not totally sure what the crystals look like, though. Usually the crystallographic long axis is normal to the plate face.
JPK -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Mohamed Noor Sent: Thursday, August 04, 2016 4:59 PM To: [email protected] Subject: [ccp4bb] Anomalous data collection from long unit cell axis Dear all I am trying to get an anomalous dataset at Fe K edge for my protein. While I can routinely get native datasets to a resolution of 2.5-3 A, the high radiation damage coupled with non-isomorphism is preventing me from getting a high multiplicity anomalous dataset. The best that I have got so far has an anomalous signal to 4.5 A but this was not enough for phasing (I tried CRANK2 and phenix.autosol) with various options. The SG is C 2221, with unit cell of about 130, 420, 85. Secondly, the crystals are not perfectly shaped like those 'usual' ones. On one side, they are almost flat like a flying saucer (for a lack of better description). The Rmerge then becomes wavy every 80 degrees or so. The protein is about 60 kDa with 5 Fe (mixture of heme and [Fe-S]) per monomer. The synchrotron has a PILATUS detector. Are there any helpful hints that you can share? Thanks. Mohamed
