Hi Nice of Jacob to mention the paper below but I don't think it is relevant to these patterns (well it might not be relevant to anything!).
I think James has given the most likely explanation. The AB type stacking disorder he mentioned is similar to the type in the paper I referenced. I think James is also right in saying the intensities of the preserved sharp spots can still be used. The point Jacob and others made about the repeats of strong intensity (e.g. every 5 spots in one direction) must be relevant. Can we have unit cell dimensions and any other details.? Cheers Colin ________________________________ From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Jacob Keller Sent: 28 January 2009 18:05 To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] small lines in diffraction pattern Acta Cryst. (1998). D54, 848-853 [ doi:10.1107/S0907444998001875 <http://dx.doi.org/10.1107/S0907444998001875> ] A Description of Imperfections in Protein Crystals C. Nave <http://scripts.iucr.org/cgi-bin/citedin?search_on=name&author_name=Nave ,%20C.> Abstract: An analysis is given of the contribution of various crystal imperfections to the rocking widths of reflections and the divergence of the diffracted beams. The crystal imperfections are the angular spread of the mosaic blocks in the crystal, the size of the mosaic blocks and the variation in cell dimensions between blocks. The analysis has implications for improving crystal perfection, defining data-collection requirements and for data-processing procedures. Measurements on crystals of tetragonal lysozyme at room temperature and 100 K were made in order to illustrate how parameters describing the crystal imperfections can be obtained. At 100 K, the dominant imperfection appeared to be a variation in unit-cell dimensions in the crystal. ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program Dallos Laboratory F. Searle 1-240 2240 Campus Drive Evanston IL 60208 lab: 847.491.2438 cel: 773.608.9185 email: j-kell...@northwestern.edu <mailto:j-kell...@northwestern.edu> ******************************************* ----- Original Message ----- From: Jacob Keller <mailto:j-kell...@md.northwestern.edu> To: CCP4BB@JISCMAIL.AC.UK <mailto:CCP4BB@JISCMAIL.AC.UK> Sent: Wednesday, January 28, 2009 11:57 AM Subject: Re: [ccp4bb] small lines in diffraction pattern I had thought that in a previous thread, we had all come to a consensus that actually the largest source of what is normally explained as "mosaicity" is really differences in unit cell size, due perhaps to uneven shrinkage in crystals upon freezing or otherwise. I believe that there was actually an acta cryst paper which investigated all of the various ingredients of "mosaicity" which supports this (this is why I said it.) Jacob ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program Dallos Laboratory F. Searle 1-240 2240 Campus Drive Evanston IL 60208 lab: 847.491.2438 cel: 773.608.9185 email: j-kell...@northwestern.edu <mailto:j-kell...@northwestern.edu> ******************************************* <DIV><FONT size="1" color="gray">This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom </FONT></DIV> -- Scanned by iCritical.
