There are now quite a few structures solved by ED of 3D crystals, esp by Tamir Gonen's group here at Janelia, and a quick count in the pdb yields ~15 3D-crystal ED structures, some of which are not released. They're getting better at it all the time. I guess the news has not spread as much as I thought. FYI, last I checked they were looking for good samples to try, although you'd have to contact Tamir about that to see whether it's still true, or whether they've now got their hands full.
All the best,
Jacob Keller
-----Original Message-----
From: Tim Gruene [mailto:[log in to unmask]]
Sent: Wednesday, March 01, 2017 2:22 PM
To: Keller, Jacob <[log in to unmask]>
Cc: [log in to unmask]
Subject: Re: [ccp4bb] How to refine this needle crystal of membrane complex?
Dear Jacob, dear TO,
(I have wondered what can be 'micro' about diffraction - would you know?)
it would be very exciting to get the structure by electron diffraction - as much as I know it would be the first new structure solved from a 3D crystal with electron radiation in the PDB. You would have to contact one of the 3-4 labs that to electron diffraction of protein samples (Abrahams, Gonen, Hovmoeller / Zou (possibly), and Yonekura/Toyoshima in alphabetic order). The first and the last group are equipped with sensitive hybrid pixel detectors that might help.
A good test to get an idea about the resolution you might get from electron diffraction is to scratch up as many of your crystals and analyse the powder pattern with a strong X-ray source (synchrotron, or very good home source).
Note that when you can see the crystals with a light microscope, they are most likely too big for electron diffraction - you might end up seeing a black screen with no electron penetrating your samples.
Best regards,
Tim
On Wednesday, March 1, 2017 1:59:44 PM CET Keller, Jacob wrote:
> Although trying to refine the crystals is perhaps the most
> straightforward thing, you might consider trying micro electron
> diffraction (micro-ED) with the existing samples—the technique is
> working increasingly better, and would work well with your tiny
> crystals. Look at Tamir Gonen’s recent papers for more info.
> All the best,
>
> Jacob Keller
>
> From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of ???
> Sent: Wednesday, March 01, 2017 3:53 AM
> To: [log in to unmask]
> Subject: [ccp4bb] How to refine this needle crystal of membrane complex?
>
> Dear all,
> I am trying to obtain crystals of membrane complex. Now, I have
> obtained the complex with appropriate stoichiometry after a series of
> purification in DDM, then I get extremely thin needles (as shown in
> figure) in some conditions such as 28% MPD, 0.1 M NaAc pH 4.5 or 45%
> MPD,0.1 M Bis-Tris pH 6.5, 0.2 M CaCl2. However, there are not any
> improvements through changing the concentration of precipitants/salts
> or adding the additives/detergents to the protein.
> I would be very happy if anybody could give me some advice about this
> crystal refinement.
> With best regards.
>
>
> [cid:image001.png@01D2926A.28CB0C70]
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Tim Gruene
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