[ccp4bb]: a question on crystallization

[Masato Kikkawa <aa06051@m.ecc.u-tokyo.ac.jp>]

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Dear CCP4BB readers,

I have a non-CCP4 question.

I'm trying to crystallize a protein inhibitor,
M.W. is about 40000, and evaluating the
result of sparse matrix screening now.
(Hampton Res. Crystal Screen #1, 2)

Sometimes, I can find 'oil drops' in the
hanging drops. To be specific, the condition
is 10 ~ 20 % ofPEG4000 and pH 7 ~ 8.

What is the 'nature' of this 'oil drop'?
Should I try Grid Screen or Additive Screen
on these conditions? Can oil drops or
amorphous crystals turn into good crystals?
What can I learn from these outcomes?

I'll really appreciate any comments.

Best regards,

Masato
--
Masato Kikkawa
Graduate Student
Univ. Tokyo