Re: [ccp4bb] Strange diffraction images

4 bulletin board on behalf of Jacob Keller Sent: Mon 8/27/2007 10:44 AM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Strange diffraction images What a beautiful and interesting diffraction pattern! To me, it seems that there is a blurred set of spots with different cell dimensions, although near

[ccp4bb] AW: [ccp4bb] Strange diffraction images

: [ccp4bb] Strange diffraction images I have a case that is similar to this, or at least visually similar by diffraction pattern(ie. strong/weak intensities). I think my situation is due to a pseudo-translation. I say this my defining of pseudo translation as basically

Re: [ccp4bb] Strange diffraction images

1079-1090. Boaz - Original Message - From: "George M. Sheldrick" <[EMAIL PROTECTED]> Date: Monday, August 27, 2007 18:49 Subject: Re: [ccp4bb] Strange diffraction images To: CCP4BB@JISCMAIL.AC.UK > Some small molecule crystallographers have specialized in &g

Re: [ccp4bb] Strange diffraction images

I think if there had been a case of a protein quasicrystal, it would have made the cover of Nature Here are some papers about quasicrystals: 1: Proc Natl Acad Sci U S A. 1996 Dec 10;93(25):14267-70. New perspectives on forbidden symmetries, quasicrystals, and Penrose tilings. Stein

Re: [ccp4bb] Strange diffraction images

I believe Wayne Hendrickson's lab has had such a case with a 10-fold symmetric mollusc hemocyanin crystal. This must have been in the early 90's and to my knowlwedge they were never able to solve the structure even though it diffracted beyond 2 Anstrom. I'm not sure if this work has been publi

Re: [ccp4bb] Strange diffraction images

> As a side note, Xtriage > doesn't think things are twinned as was suggested for one some of the other > diffraction patterns discussed earlier today. Hi Todd, Detection of twinning in the presence of pseudo translations / and or NCS parallel to the twin law is difficult and using model based te

Re: [ccp4bb] Strange diffraction images

The left-out spots would be the diffuse spots, which I assume were not indexed/integrated. The sharp spots were presumably used to solve the structure. JPK ==Original message text=== On Mon, 27 Aug 2007 11:36:08 am CDT Raji Edayathumangalam wrote: Very dumb question per

Re: [ccp4bb] Strange diffraction images

Very dumb question perhaps: If there were two interpenetrating lattices of slightly different cell dimensions, would we not expect that the indexing program would leave out a lot of the spots as "unpredicted" or "uncovered"? Could someone clarify with respect to the diffraction pattern that has

Re: [ccp4bb] Strange diffraction images - PS

Apologies, part of my previous message was missing and part appeared twice. Here is another try: Jacob, Some small molecule crystallographers have specialized in solving and refining structures that, exactly as you describe it, consist of two interpenetrating, non-commensurate lattices. The usua

Re: [ccp4bb] Strange diffraction images

I am still eagerly awaiting a biomacromolecular quasicrystal with a five-fold symmetric diffraction pattern. It seems that this is entirely possible, if one gets roughly Penrose-tile shaped oligomers somehow. But wow, how would you solve that thing? I guess one would have to modify software fr

Re: [ccp4bb] Strange diffraction images

Some small molecule crystallographers have specialized in solving and refining structures that, exactly as you describe it, consist of two (or more) interpenetrating, non-commensurable lattices. The usual approach is to decribe the crystal in up to six dimensional space. The programs SAINT and

[ccp4bb] Strange diffraction images

What a beautiful and interesting diffraction pattern! To me, it seems that there is a blurred set of spots with different cell dimensions, although nearly the same, underlying the ordered diffraction pattern. A possible interpretation occurred to me, that the ordered part of the crystal is suppo