Hi, The closest example I can think of is the extra density that was found in the groove of the MHC class I structure (Bjorkman et al., long time ago) which turned out to be a peptide that was co-purified. As we all know, it turned out to be one of the major findings of this study as it pointed to the way MHC's recognize peptides.
Cheers, Boaz Boaz Shaanan, Ph.D. Dept. of Life Sciences Ben-Gurion University of the Negev Beer-Sheva 84105 Israel E-mail: bshaa...@bgu.ac.il Phone: 972-8-647-2220 Skype: boaz.shaanan Fax: 972-8-647-2992 or 972-8-646-1710 ________________________________________ From: CCP4 bulletin board [CCP4BB@JISCMAIL.AC.UK] on behalf of Leonard Thomas [lmtho...@ou.edu] Sent: Thursday, July 19, 2012 1:12 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] peptide fragment Hello All, I have been working on a structure for one of the research groups here and have come across a peptide fragment of about 10 residues. The protein forms a tetramer and the peptide is found between two of the monomers. The protein itself does not require a peptide for function or formation for that matter. Has anyone come across similar things? and have a reference. We are trying to figure out where it may have come from. My best guess so far is from somewhere in the purification though I have no idea how long the protein sat around before crystallization. Cheers, Leonard Thomas Ph.D. Macromolecular Crystallography Laboratory Manager University of Oklahoma Department of Chemistry and Biochemistry Stephenson Life Sciences Research Center 101 Stephenson Parkway Norman, OK 73019-5251 lmtho...@ou.edu http://barlywine.chem.ou.edu Office: (405)325-1126 Lab: (405)325-7571