Re: [ccp4bb] Unknown electron density blob

[Boaz Shaanan]

Hi, Could it be a segment of peg3350?   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 Uma Gabale [00000ebb5dcf3eaa-dmarc-requ...@jiscmail.ac.uk] Sent: Tuesday, January 24, 2017 7:19 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Unknown electron density blob Dear all, While refining a structure at 2.5 A resolution, we observed a semi-circular/crescent shaped electron density blob as shown in the attached picture. We have been unable to identify it so far, and would appreciate any help in identification. The protein was expressed in E. coli BL21(DE3), purified on Ni-NTA followed by gel filtration. The purification buffers included Tris and NaCl (no detergent/ other ingredients except for imidazole for Ni-NTA). Crystallization condition had HEPES and PEG3350; no cryoprotectant was used. The blob is surrounded by residues Trp, Thr, Gln, Arg, and Phe. Thanks and regards, Uma. -- Uma Gabale, PhD Research Associate Molecular and Cellular Biochemistry Indiana University Bloomington