Renaturation of proteins from 8M Urea - references?

[David I Resnick]

Hi,

I'm expressing a ~130 amino acid protein fragment in E. coli.  After
solubilization in 8 M Urea, I purify it using a His6 tag.  I then want
to get rid of the urea (and pray that it will fold).  Everything I've
tried so far (not many things, but a few) has resulted in
precipitation.  Anyone out there know of a comprehensive reference for
this sort of thing?  Any ideas???

Thanks!

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       David Resnick                           dresnick at athena.mit.edu