Leu Zipper Blues

Simon Easterbrook-Smith sbe at biochem.usyd.edu.au
Fri Mar 21 23:37:07 EST 1997

In article <Pine.GSO.3.96.970321100824.18039A-100000 at sun1.oulu.fi>, Pete
<pkursula at cc.oulu.fi> wrote:

|| Suppose that you found out that your protein has a leucine zipper
|| structure and forms tight dimers... Is possible to separate these into
|| monomers?

Yes, using denaturing conditions (low pH, urea, GuHCl, etc etc). If your
protein is small enough then you should be able to get pure monomer by
RP-HPLC - see (ahem) Biochemistry 35: 9069-9075 (1996) for how we have done
this for Jun and Fos LZ.

|| On the other hand, if one is studying the function/ligands of
|| the protein in question, is this feasible?

Umm..., feasible in what sense?

||Are these proteins present in the cell ONLY as dimers or is there an
||equilibrium that would enable the  monomeric form to also have a distinct

This will depend on the values for the equilibrium constant and the
cellular concentration of your protein - ie, if the concn is much greater
than Kequil, then most will be dimer but most will be monomer if the concn
is much less than Kequil. See Science 245: 646-648 (1989) for a discussion
of this in the case of the Jun and Fos LZ.

Dr Simon B Easterbrook-Smith    Voice: (+) 612 9351 3905
Department of Biochemistry      FAX: (+) 612 9351 4726
University of Sydney            Email: sbe at biochem.usyd.edu.au
Sydney NSW 2006
Every complex question has a simple, straight-forward,
easy to understand, wrong, answer.

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