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[ccp4bb]: Co-crystallisation with hydrophobic ligands
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Many thanks to everyone who emailed, suggestions were really helpful.
Here is a summary of responses:
David Schuller:
1. Co-concentrate ligand with protein: (This is actually something I
tried before posting my question; it seems to work with some ligands
but with others concentration causes both protein and ligand to
precipitate.)
Gitay Kryger & Jeroen Brandsen:
2. Soak/Co-crystallise the crystal in drop containing solid ligand.
George Kontopidis:
3. If Kd is slow, then excess of ligand is not required and unbound
ligand will be at low effective concentration anyway. (In fact adding
excess will not give much greater occupancy).
Eiichi Tsuji:
4. Use 1.3 dimethyl -2-imidazolidinone (DMI) instead of DMSO/DMF etc.
DMI is miscible in water and can tolerate up to 15%(v/v) against
protein. (I hadnt heard of this solvent before, but im going to try
it!).
Michal Harel:
5. Stir the ligand extensively in buffer or buffer+DMSO, then spin down
and use the solution in co-xtallization.
Cheers,
Leo