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 On Apr 6, 2012, at 11:41 AM, 杨贝 wrote: 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 ...................... Jürgen Bosch Johns Hopkins University Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Office: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-2926 http://web.mac.com/bosch_lab/
