Well, this is of course just my undereducated two cents but the first question I'd ask is: asuming that dataset #2 is a real derivative - can I find realistic sites? What are you basing your resolution cutoff on - in the diffraction images, do you visually observe anisotropy?
It's not uncommon for derivatives to change diffraction properties of the crystal anisotropically - for instance if a derivative site happens to be on a major crystal contact in a specific direction within the crystal. Can you get better data (better crystals)? It's awfully hard to trace experimental maps at 4+ A especially if you have no NCS multiples to help you with crummy phases. Artem "Nothing is built on stone; all is built on sand, but we must build as if the sand were stone" Jorge Luis Borges -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Francis E Reyes Sent: Wednesday, August 26, 2009 4:23 PM To: [email protected] Subject: [ccp4bb] suggestions for SIR with strong diffraction anisotropy in the derivative Hi all I'm trying SIR on my crystal both are C222. Native Cell Dimensions: 97.66 243.45 87.62 90 90 90 Resolution: 4.3 Derivative Cell Dimensions: 96.9100 244.66 87.61 90 90 90 Resolution: 4.7 . I plan to scale together using FHScal. Ctruncate says that my derivative has strong diffraction anisotropy. How concerned should I be about this at the level of phasing? Is there anything to be done with the anisotropy issue? Thanks --------------------------------------------- Francis Reyes M.Sc. 215 UCB University of Colorado at Boulder gpg --keyserver pgp.mit.edu --recv-keys 67BA8D5D 8AE2 F2F4 90F7 9640 28BC 686F 78FD 6669 67BA 8D5D
