Hello All,
I am trying to crystallise a heterodimeric transcription factor complex bound
to DNA. At the moment I have a construct which crystallises in many different
conditions, all containing a PEG (3350, 4K, 6K, 8K) as precipitant along with
various buffers and/or salts. When fine screening (in hanging drops) around
these conditions I commonly get a shower of microcrystals at 20% (or higher)
PEG. At lower PEG concentrations the crystals become more round and eventually
the drops progress to phase separation (around 15% PEG).
Lowering the protein concentration in the drops results in similar numbers of
crystals forming, which end up smaller in size. I have tried seeding with the
microcrystals from higher to lower PEG concentrations which results in crystal
melting/phase separation.
Also, the best crystals seem to grow on the glass slide and when I try to move
them or pick them up, they are quite soft and hard to handle.
Any advice on how to optimise conditions for growth of larger crystals and also
tips for handling these soft crystals would be great.
Thanks, Scott
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