You should try collecting a data set at the Br- edge, and perhaps other wavelengths for MAD. I would think that you will locate at least one or two Br-'s, which should be plenty with only 9 kD. If you want, you could collect similar crystals with either KCl or KI, then do either SIRAS or MIRAS.
Jacob Keller ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program Dallos Laboratory F. Searle 1-240 2240 Campus Drive Evanston IL 60208 lab: 847.491.2438 cel: 773.608.9185 email: [EMAIL PROTECTED] ******************************************* ----- Original Message ----- From: amit sharma To: CCP4BB@JISCMAIL.AC.UK Sent: Thursday, September 25, 2008 6:03 AM Subject: [ccp4bb] Quick-soak Dear CCP4bbers, I have a protein molecule(~9.0 kDa) that crystallized in the presence of 0.15M KBr and HEPES pH 7.0. Since there is no homologuous structure present, I intend to perform heavy metal derivatization. I read some literature which suggested that I could carry out quick soak with 0.5M Sodium iodide. I was wondering if I could soak my crystals with a similar concentration of NaBr and collect some low resolution data at the in-house source? In addition should I try to also introduce other heavy metals? it might be worth mentioning that my protein carries no methionine/cys residues. I have no prior experience in doing this. So, it would be of great help if I could be directed towards literature/protocols pertaining to this. Any advice/suggestions would be greatly appreciated. Thanks in advance -- Amit Sharma
