Jacob, Some protein can form weak dimer, especially in low salt buffer. AUC can provide a more detailed info about your protein dimerization state.
Ray On Mar 22, 2011, at 8:23 PM, Jacob Keller <j-kell...@fsm.northwestern.edu> wrote: > Dear Crystallographers, > > I have run my protein-peptide complex several times on a GE S200 > 10/300 in buffer A (below). Today, to make a crystallization stock, I > ran the sample in buffer B, and the peak shifted from a consistent > 16.0 mL to 13.5mL, which would seem to be ~dimer MW, but I know that > SEC results change as a result of buffer conditions. Could this > drastic a shift be due simply to buffer conditions, or could there > actually be some buffer/ion-dependent dimerization going on? Anyone > have a similar experience? > > A: (20mM HEPES, 50mM NaCl, and 5mM CaCl2 pH'd to 8.1 w/ TRIS base) > B: (5mM HEPES, 0mM NaCl, and 1mM CaCl, pH'd to 7.5 w/ TRIS base.) > > Jacob Keller > > ******************************************* > Jacob Pearson Keller > Northwestern University > Medical Scientist Training Program > cel: 773.608.9185 > email: j-kell...@northwestern.edu > *******************************************
