Hi, I wouldn't worry about Se oxidation. In principle having a mix of oxidized/reduced seleniums is unfavorable, as you'll have less signal at the edge (broadening). However, all-oxidized Se apparently makes things better (sharper and more intense peak; I forgot the reference, i think it may have been an Acta Cryst. D paper). We never bother with adding EDTA and/or reducing agents and haven't had problems determining structures by SAD. You should be fine. Cheers, Bert Bert van den Berg University of Massachusetts Medical School Program in Molecular Medicine Biotech II, 373 Plantation Street, Suite 115 Worcester MA 01605 Phone: 508 856 1201 (office); 508 856 1211 (lab) e-mail: bert.vandenb...@umassmed.edu http://www.umassmed.edu/pmm/faculty/vandenberg.cfm
________________________________ From: CCP4 bulletin board on behalf of aka akaka Sent: Mon 2/9/2009 1:27 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Se oxidation Dear All I would like to know whether oxidation of Se entails any problem for SAD or MAD experiments and/ or how to resolve it. Cannot use DTT or reducing agents in my protein (extracellular and disulphide bonds are important). Thanks Dr. R.Depetris Weill Cornell Medical College ________________________________ Get 5 GB of storage with Windows Live Hotmail. Sign up today. <http://windowslive.com/Explore/Hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_5gb_112008>
