What is the solubility of substrate? Try analogues with higher solubility. The 2mM may not be 2mM in the solution!
The fact that you added there does not mean that it goes to the solution. If solubility is indeed high and Ki/[solubility]>1 you should be able to see some density in the binding site. If not then check the following is binding site accessible in the crystallise protein? If binding site is blocked in the crystal lattice substrate cannot go there. The crystallisation conditions you try to crystallise protein with substrate are different from the native (unliganded)? May be you have to try different conditions George _____ From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Priya Mudgal Sent: Thursday, November 27, 2008 11:09 PM To: [email protected] Subject: [ccp4bb] Co-crystallization Dear All, I am trying to co-crystallize a protein with substrate/substrate analogue and for some reason it is not working. I have tried to co-crystallize with upto 2 mM substrate and it does not bind. The protein precipitates out if I go higher concentration. Soaking does not work either. Is there any suggestion that I should try before I give up on this. Thanks a lot. Priya -- Priya Mudgal PhD Student Duke University
