There should be two broad types of statistical disorder, short range and long range. The latter for example could consist of two distinct populations of crystal with near identical unit cells so the spots nearly overlap in reciprocal space. If there is a layer structure, shift disorder between layers could occur.
These cases should be distinguishable by an examination of the diffraction patterns (probably a bit late for 2ts1). Streaks in certain directions could occur or broader diffuse features. Also perhaps anisotropic resolution. If two populations of crystal, perhaps the spots would be slightly split (in x,y or phi). Main point is if proposing disorder, there should be consequences which could be tested. Whether it is worthwhile to do so is of course another issue. Colin ------------------------------------------- Just to give a concrete example of Randy's point, PDB entry 2ts1 for tyrosyl tRNA synthetase has "layers" of molecules with no contact between the layers. This is because the domain (residues 320-419) that was providing the contacts in this direction was disordered and could not be modelled (there was very little density in this region). It is perhaps surprising that in spite of the disorder the crystals diffracted very well (2.3Å data collected on film). Andrew On 6 Feb 2015, at 11:16, Randy Read <rj...@cam.ac.uk<mailto:rj...@cam.ac.uk>> wrote: Actually, if you go back through the archive of CCP4-BB from the first time this came up, I think you'll find that there are real crystals with apparent gaps in the packing. This can arise because of statistical disorder, where there are two or more ways that a statistically-disordered layer in the crystal can mediate the interaction between ordered layers. So not finding a connected packing is something to look closely at and worry about, but it doesn't necessarily indicate that somebody did a bad job of making up a structure. Randy On 6 Feb 2015, at 11:09, Robbie Joosten <robbie_joos...@hotmail.com<mailto:robbie_joos...@hotmail.com>> wrote: -- 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
