A while back Randy Read informed me of the capacity in Phaser for doing log-likelihood anomalous maps, and I was very happy with the results. Cys-sulfurs showed high peaks even though the incident x-rays were 1 Ang. I could also see what seemed to be chlorides and maybe potassiums, and even what also seemed to be shards of x-ray-damaged sulfurs or seleniums spangling the inside of an adjacent internal cavity in the protein. Very powerful those maps.
Accordingly, maybe make one of those maps, and send out the next couple of snapshots? At 7.4 sigma and what appears to be pretty good resolution, you will probably have something with a modicum of anomalous signal in there. Also it would be good to know the chemical history of the protein from purification onwards (like BME and so on). Also including what was in the protein stock itself... JPK -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of RHYS GRINTER Sent: Tuesday, January 13, 2015 7:49 PM To: [email protected] Subject: [ccp4bb] Post-translational modification of cystine Hi All, I think everyone enjoys this game, so to save me a trawl through the literature can anyone help me interpret this density? The density on the end extents to 7.4 sigma, so something reasonably large. I guess it's some kind of PTM of the cystine residues, but nothing specific springs to mind. the crystallization conditions were 0.1 M CITRIC ACID, PH 5.0, 2.0 M NACL. Cheers, Rhys
