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 *******************************************
