This nicely illustrates the danger of using too low resolution data to compute the SRF (I'm referring to an earlier BB discussion on this subject, where it was suggested to cut out the high resolution data, against, it seems to me, all rationale). You should be using as high resolution valid data as possible (it goes without saying that using rubbish data at any resolution won't help!).
Additionally I always sharpen SRF maps (and depending on the sequence similarity the XRF sometimes also) by using E's (from Ecalc) instead of F's in order to magnify the contribution of the high res data. This reduces the peak widths somewhat (though not as much as one might think) and reduces the chance of this kind of mis-interpretation. In the case of complicated NCS with many peaks it may also enable you to see important detail you might otherwise have missed. The 3-fold peak will be *very* strong, it's crystallographic after all: seeing it 'leaking' onto adjacent sections and even stretching as far as the kappa=180 section is common, particularly with low resolution data and/or using F's. As I said 4-fold NCS is extremely unusual, in fact I'm not aware of a single example, thought I guess there must be some. 4 mols arranged in 222 NCS is of course very common. Cheers -- Ian > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Francis E Reyes > Sent: 22 July 2009 02:53 > To: Charlie Bond > Cc: CCP4 bulletin board > Subject: Re: [ccp4bb] Self Rotation map in R32? > > On Jul 21, 2009, at 7:50 PM, Charlie Bond wrote: > > > By 'on the same scale' do you mean it is 40% of the height of the > > K=120 peak? > > Could it be a 'tail' of the kappa=120 degree peak? If you look at > > 95, 100, 110 etc does the peak persist and get stronger? I'm not > > sure how meaningful this would be, but I just had a look at the > > polarrfn output of a C2 dataset and I can still see 40% of the K=180 > > peak present at K=150. > > > > Cheers, > > Charlie > > > Hmm It does look like it's the strongest in the kappa=120 slice. If > the 3 fold is that strong it would also explain how I also observe the > same peak in the kappa=180 slice. > > > FR > > --------------------------------------------- > Francis Reyes M.Sc. > 215 UCB > University of Colorado at Boulder > > gpg --keyserver pgp.mit.edu --recv-keys 67BA8D5D > > 8AE2 F2F4 90F7 9640 28BC 686F 78FD 6669 67BA 8D5D Disclaimer This communication is confidential and may contain privileged information intended solely for the named addressee(s). It may not be used or disclosed except for the purpose for which it has been sent. If you are not the intended recipient you must not review, use, disclose, copy, distribute or take any action in reliance upon it. If you have received this communication in error, please notify Astex Therapeutics Ltd by emailing [email protected] and destroy all copies of the message and any attached documents. Astex Therapeutics Ltd monitors, controls and protects all its messaging traffic in compliance with its corporate email policy. The Company accepts no liability or responsibility for any onward transmission or use of emails and attachments having left the Astex Therapeutics domain. Unless expressly stated, opinions in this message are those of the individual sender and not of Astex Therapeutics Ltd. The recipient should check this email and any attachments for the presence of computer viruses. Astex Therapeutics Ltd accepts no liability for damage caused by any virus transmitted by this email. E-mail is susceptible to data corruption, interception, unauthorized amendment, and tampering, Astex Therapeutics Ltd only send and receive e-mails on the basis that the Company is not liable for any such alteration or any consequences thereof. Astex Therapeutics Ltd., Registered in England at 436 Cambridge Science Park, Cambridge CB4 0QA under number 3751674
