[ccp4bb] soaking problem

[Samy kannu]

Dear all,

One of my enzymes crystallized in 0.1 M citric acid pH 3.5 and 25% PEK 3350.
The structure solution reveals, citrate molecule is occupying the active
site.
Moreover citrate mediates the dimer formation.
I tried crystallization in the same condition with ligand using soaking with
different concentrations of ligands and lower concentration of citric acid
(below 0.5 M of citric acid, crystals are broken). Cocrystallization also
tried.
I collected several data sets with these combinations.
The Structure solutions from all these data sets give only citrate complex.
I could not get the enzyme-ligand complex

I found crystals only in citrate condition.

Any suggestions !!

Thanks.
Skkannu

[ccp4bb] citrate blocks the active site

[Samy kannu]

 Dear all,

 One of my enzymes crystallized in 0.1 M citric acid pH 3.5 and 25% PEK
 3350. The structure solution reveals, citrate molecule is occupying the
 active site.
 Moreover citrate mediates the dimer formation.
 I tried crystallization in the same condition with ligand using soaking
 with different concentrations of ligands and lower concentration of citric
 acid (below 0.5 M of citric acid, crystals are broken). Cocrystallization
 also tried.
 I collected several data sets with these combinations.
 The Structure solutions from all these data sets give only citrate complex.

 I found crystals only in citrate condition.

 Any suggestions !!

 Thanks.
 Skkannu