Hi Boaz thanks for the advice - Yes your suggestions are very useful thank you! I actually have not tried Phaser with the P4 data so I will give that a shot. Curiously Pointless selects P21 from P4 and P421/3 from P21... I tried MolRep in P1 but Phaser failed to find any solution though perhaps I did not pursue it enough... I think it is entirely possible that the space group I have , as in your example, may be something other than P21 etc Never tried Zanadu sounds interesting I'll take a look... We have new crystals... I was wanting to solve the twinned data to get some initial info etc and as a crystallography problem/exercise not having come across it yet... thanks again Best Gina
________________________________ From: Boaz Shaanan [mailto:bshaa...@bgu.ac.il] Sent: Friday, October 01, 2010 5:18 PM To: Clayton, Gina Martyn Subject: Re: [ccp4bb] Twinned data Hi Gina, I've had a similar situation and here are some suggestions/ ideas: 1) You could try to run Phaser on the the data processed as P4 BEFORE detwinning and ask it to try all the possible space groups including the P422 and related ones. 2) Before step 1 or in parallel or following it, I would run the P4 processed data (again NOT detwinned) through pointless and/or xtriage to see whether they can give some indications for better choice of space group. 3) In my case, only running Phaser in P1 gave me a solution (the data were initially processed as P4 but I reprocessed them in P1 for that purpose). It's worth you trying too. 4) Eventually, I ran the P1 model (8 mols.) and data in Zanuda (on the York site) and that gave me a new space group choice (P21212). When I ran Phaser in this space group (after reprocessing the data again) it also gave a good solution which I'm now refining (with twinning) either in Phenix or refmac but without detwinning, since the program do this for you internally (I'm sure about refmac and assume it's the same in Phenix). I hope you'll find some of this helpful. Cheers, Boaz ----- Original Message ----- From: "Clayton, Gina Martyn" <gina_clay...@merck.com> Date: Friday, October 1, 2010 21:28 Subject: [ccp4bb] Twinned data To: CCP4BB@JISCMAIL.AC.UK > Hi there > > Just wondering if anyone has any suggestions how I can deal, if > possible, with the following situation -. My first > encounter with > twinned data... > > which initially indexed as p43/p41 cell dimensions 58.4 58.4 61 > 90 90 > 90. > Having seen the Matthews Coefficient for the solvent content of > the unit > cell as 16% I discovered the data are merohedrally twinned with twin > fraction given as 0.1. > > I reprocessed the data as p1, p2 p21, c2221 (Rsymm etc indicates wrong > space group, Mats Coeff 16%) p4 etc. In p2 the (pseudo) twin > fraction is > given as 0.43 (Mats Coeff 60% solvent 2.7 mol/ASU). > > I ran Detwin (ccp4) on the p2 p21 data with alternate operators as > indicated by Xtriage in Phenix. I have had no > molecular replacement > solution i.e. Molrep rotational searches are not giving peaks > and Phaser > has not found a solution (nor with alternates of the search "model"). > > Does anyone have any suggestions/best paper to consult etc based on > their experience of twinned data (aside from sort the crystals out...) > or should I "throw in the towell?" > > Thanks in advance for any information and advice > > Gina > > > > > Notice: This e-mail message, together with any > attachments, contains > information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, > New Jersey, USA 08889), and/or its affiliates Direct contact > informationfor affiliates is available at > http://www.merck.com/contact/contacts.html) that may be confidential, > proprietary copyrighted and/or legally privileged. It is > intended solely > for the use of the individual or entity named on this message. > If you are > not the intended recipient, and have received this message in error, > please notify us immediately by reply e-mail and then delete it > from > your system. > Boaz Shaanan, Ph.D. Dept. of Life Sciences Ben-Gurion University of the Negev Beer-Sheva 84105 Israel Phone: 972-8-647-2220 ; Fax: 646-1710 Skype: boaz.shaanan Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, New Jersey, USA 08889), and/or its affiliates Direct contact information for affiliates is available at http://www.merck.com/contact/contacts.html) that may be confidential, proprietary copyrighted and/or legally privileged. It is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please notify us immediately by reply e-mail and then delete it from your system.
