Dear CCP4bbers,
I am now working on a DNA binding protein and the purity of the protein is quite good, however the results of DLS showed that the protein aggregates terribly in quite a lot of different buffer conditions I tried and still no crystals can be obtained. So I am going to co-crystallize the protein in complex with DNA. I synthesized the oligonucleotides varying different numbers of basepairs to determine the optimal length which can bound to my protein by EMSA. I dissoved the oligos in the buffer containing 50mM Tris-HCl, 100mM NaCl, 10mM MgCl2 and 1mM DTT, pH 7.9 and then annealed the DNA into the double stranded form at a final concentration of 50uM. When I performed the EMSA experiment, I mixed the purified protein with the dsDNA at the molecular ratio approximately 1:1, but white precipitate was generated as I mixed them. Does anyone have this kinds of experience when working on DNA binding proteins and co-crystallizing the protein-DNA complex? Any suggestions from yours will be appreciated. Thank you all. Ru Heng _________________________________________________________________ 上Windows Live 中国首页，下载最新版Messenger！ http://www.windowslive.cn
