Re: [ccp4bb] PEG refinement

[Boaz Shaanan]

Hi, I usually pick up the one that fits best the map (there are several PEG monomers in the ccp4 monomer library to choose from). You should bear in mind that PEG's are a mixture of molecules, quite often floppy, so whatever fits best is the best choice.   Good luck,                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 Albert Guskov [albert.gus...@googlemail.com] Sent: Tuesday, December 18, 2012 1:05 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] PEG refinement Dear all, is there any consensus about PEG refinement? I'm currently refining several structures with a lot of bound PEG molecules. However I'm completely confused now which ligand description to use. For example, a search in Hic up database reveals 12 possible descriptions for PEG, 5 of them used for PEG400, but with completely different length ranging from C8 (number of carbon atoms), ligand ID PG4 up to C24, ligand ID 12P. Other descriptions are also quite confusable, for example PEG 8K (ligand id PEU) is C55H112O28, but apparently shorter PEG1500 (ligand id 15P) is C69H140O35. Shall the crystallography community come up with some standardised list of descriptions for PEG molecules?  With best regards, Albert