Yes, very much so. In fact it's one of the old-school reversible protection methods for the -SH group. Many commonly used heavy atoms avidly bind -SH but only weakly bind -S-S- (although Pt(IV) compounds seem to be fairly interested in -S-S- in my experience).
You can break this bond with TCEP - or just abandon BME and use TCEP throughout if your protein allows it. Good luck, Artem --- When the Weasel comes to give New Year's greetings to the Chickens no good intentions are in his mind. -----Original Message----- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Wataru Kagawa Sent: Tuesday, May 12, 2009 10:18 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Mercaptoethanol Hi. We are trying to prepare heavy atom derivatives of a protein in which a surface residue was mutated to cysteine. Mass spectrometry of the purified cysteine mutant showed an additional peak with a molecular mass that correspond to a mercaptoethanol-bound cysteine mutant. I am wondering whether the bound mercaptoethanol prevents the heavy atom from binding to the cysteine residue. Any information would be greatly appreciated. Wataru Kagawa
