Dear All, In order to phase, I intend to derivatize my protein(30kDa)-DNA(7.2kDa) complex with heavy atoms. I wanted to know which was the better way to do it: longer soaks at lower heavy atom concentration, or shorter soaks with higher concentration of heavy atom. Also, what concentrations and time is generally used in either case. The crystals came up in pH 6.0 buffer and the protein contains 1Cys, 3Met and 3His residues.
I would appreciate any advice or link to the literature. Many thanks in advance Amit Sharma, Postdoctoral Fellow, Department of Biophysics, Johns Hopkins University, Baltimore, MD21218