Re: [ccp4bb]: to improve crystal diffraction: looking for ideas

[Noinaj]

RG,   Just a quick suggestion since you seem to have tried most other things.  But first, is this protein an enzyme?  If not, does it have binding partners or ligands?  My thought is that by either using substrates (inhibitors) or binding partners/ligands, you may be able to increase overall conformational stability.   I am sure that you have tried dehydration techniques also, but those didn't work for me either.  But, I did try quick dunking crystals in 50% PEG (or other cryoprotectant) and that did miracles for me.  Of course, different protein, different miracles.   Best of Luck!     Cheers, Nick         ----- Original Message ----- From: Rongjin Guan To: CCP4 Bulletin Board Sent: Monday, April 17, 2006 5:56 PM Subject: [ccp4bb]: to improve crystal diffraction: looking for ideas Dear All,   We have a protein that can be esaily crystallized, but diffracts very weak. We tried many mutations/diffrent constructs, the problem is still there.   Crystals are very beautiful, big, and appear in many conditions with the same shape (same space group, too). None of them diffract better than 4 A.   I would appreciate if some one can provide some "fresh" ideas. We have tried many things, before crystallization, after crystallization and during data collection, etc. Years passed, no impovement. Very frustrating. Any ideas will be welcome.   Thanks   Rongjin Guan