Hi all, I recently encountered a modified surface cysteine residue in one of my structures. The protein is expressed in E.coli and my data is to 1.7Å so I am positive of the number of extra atoms. It really look like one of the tails (the Propanoic acid) of a TCEP molecule. TCEP was added during purification at 2 mM. I tried to look in pdb (or google) but I could not find any reference of that TCEP could do this. The modified Cystein is involved in a nice crystal contact (salt bridge) to a Lysine, and thereby stabilizing it further. Looking back at older structures of the same protein, I see the same modification of this Cys, but not as pronounced since they were done at lower resolution.
Does anyone recognize this behavior of TCEP? Or, any other ideas? Björn Kauppi Structure and Design Karo Bio AB ______________________________________________________________________ This e-mail may contain confidential information proprietary to Karo Bio AB and is meant for the intended addressee(s) only. Any unauthorized review, use, disclosure or distribution is prohibited. If you have received this message in error, please advise the sender and delete the e-mail and any attachments from your files. Thank you! ______________________________________________________________________
