off topic: the effects of spontaneous oligomerization on crystallization

From: 杨贝 <joybeiyang
Date: 6 April 2012 16:41

Dear All,

 

I have a 100KD protein which elutes as a mixture of 90% monomer and 10% dimer on HPLC, if I pool the monomer fractions and  reload them onto the column, the elution profile is still 90% monomer plus 10% dimer, and the same is true if I do so to the dimer peak. Collectively, there seems to be a equilibrium between the monomer and the dimer. So far, I have not got crystals yet, since the purity of the protein is fairly high (99% pure), I am wondering if the lack of crystallization is caused by the heterogeneity introduced by the spontaneous oligomerization, and if so, what can I do to improve the homogeneity? Will a additive/detergent screen help (this is not a membrane protein)?  

 

Any comments will be greatly appreciated!

 

Best,

 

Joy

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From: Bosch, Juergen

If you have a DLS you can try playing with different [NaCl] or pH and see if you can push the equilibrium in one direction.

Jürgen

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Jürgen Bosch