Dear Marek,
A lot may happen: Your active site might be blocked by PEG or crystal contacts,
or your sugar substrate gets converted into product and leaves the active site.
In your case I would try the following:
- soak or cocrystallize with a non-hydrolizable suger analog
- soak with as high a substrate concentration as you can get (preferably
saturated)
- try crystallizing with larger pegs (20k) which may not enter the active site.
Good luck!
Herman
________________________________
From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of
Marek Frischerkase
Sent: Tuesday, June 09, 2009 1:56 PM
To: [email protected]
Subject: [ccp4bb] soaking problems
Dear all,
I tried to soak substrate (sugar) into my enzyme-crystals. After
solving the structure I found PEG molecules instead of substrate in the active
site. Does this mean that the active site is blocked and the substrate isn´t
able to get into the enzyme-crsytals anymore? I used PEG 1000 in my
crystallisation setups. Cocrystallisation showed no success so far.
Can anyone give some suggestion what I should do?
Thanks a lot,
Marek
