Peter, I think it would depend if the substrate analog have ionizable groups? If the analog does not have ionizable groups, it is hard to imagine how the the titration of ionizable groups on the protein would impair the binding.
Chitta ----- Original Message ----- From: "Peter Hsu" <hsuu...@u.washington.edu> To: CCP4BB@JISCMAIL.AC.UK Sent: Tuesday, October 30, 2012 12:12:58 PM Subject: [ccp4bb] oof topic: pH effect on substrate analog Hi all, I'm working on a protein that I recently got crystals of. My functional studies show that the protein has optimal activity at lower pHs, while losing >90% activity at about pH8. I've been trying to soak/cocrystallize a substrate analog (small molecule) into my crystals (grown at ~pH8) with no real luck. I'm wondering, since I lack activity at this pH point, would it lead to no binding of a substrate analog? Thanks for any insights Peter
