Dear all
We are pleased to announce a practical workshop for preparation of samples for
Cryo-EM which will run from the 9th to 11th January 2017 at eBIC @ Diamond
light source. The course is funded by eBIC and the Horizon 2020 project iNEXT
(http://www.inext-eu.org ) with the support of FEI.
Back in my grad school days, we had crystals (of gamma delta resolvase large
fragment) like that: at high protein concentrations, we'd get P6422 with
1/asymmetric unit, and at lower concentrations, C2221 with 3/asymmetric unit
(with an imperfect ncs 2fold 60 degrees from the xtal fold, and very
Hi Hauke,
so your refinement results in P1 seem to say it's untwinned. I don't see (but I
may be overlooking something?) the evidence, from what you write, that it could
not be P21 or P2, because any P2 or P21 structure can be refined in P1 (but of
course not the other way round). In other
I've seen this kind of thing before.
Case 1: two crystal forms in the same droplet, C2 and C222. If you
looked closely, you could tell them apart and I was pretty good at
getting a high percentage of the desired space group by looking at the
crystal forms. The C2 form diffracted better, so I
Dear Hauke,
when you use twin refinement, your R-factor is bound to drop whether it is
twinned or not. In your case Rfree rises, which is actually hinting at your
data not being twinned. How many reflections do you have in the Rfree set?
Best,
Tim
On Friday, October 28, 2016 1:59:29 PM CEST
Dear Kay,
Thank you for your answer!
I have meanwhile processed my anomalous data also also as P1 and solved the
structure with MR-SAD in P1, which works flawlessly and gives the same
solution. Compared to P21, I now have 4 instead of 2 molecules in the ASU,
which makes sense. I then tried
Dear Hauke,
the conversion of intensities to amplitudes is an area with unsatisfactory
solutions, and the approaches of (and the assumptions made by) the different
programs differ. Low-resolution data are often anisotropic, which adds
difficulties. You could try CCP4 truncate/ctruncate and
The last I heard (which was a while ago), Windows could run the stereo
emitter over USB with a Geforce card, but Linux still needed a Quadro
card with the 3 pin mini-DIN connector. I hope this is no longer true,
but I have not heard clear information to the contrary. Note that the
text you
Hi
Something I'd do is try different programs for the indexing to see if you get
both choices with any programs - Mosflm & XDS will give you the 44
characteristic lattices and cell parameters by default (so you can easily see
if anything like the C2 cell is a straightforward transformation of
It is entirely possible (fairly common) to have two different crystals in one
drop. If the habits are the same I'd expect the same cell, but that doesn't
have to be the case. Likewise, if the habits are different I'd expect different
cells, but again that is not necessarily the case.
bert
Hi Sam,
Yes. I've had 2 different crystal forms from the same drop. C2 vs C2221.
Completely different packing, despite that fact that 2 of the cell edges
were within an angstrom or two of each other.
In the above case, I soaked ligand into the crystals, one form had ligand
bound, one didn't,
Good morning,
53 x 2 = 106
79 x 2 = 158
Awfully close to 156 and 105 in the C-group. Are you sure there is no
tricky twinning or faulty indexing of some sort - in either of these space
group assignments?
On the other hand, I have seen two different habits and different
spacegroups growing from
Dear all
Sorry for going a bit off-topic in this thread.
May I seek your advice as on whether you have experienced that crystals
being obtained from the same droplet, looking alike under microscope (rod
shape) and in fact growing possibly from a same nuclei, give two space
groups after indexing?
Hi Matt,
I guess you are talking about hardware. For a year or so, this should have
become quite cheap. A recent Nvidia Geforce card, a 120 Hz 3D Monitor and a
3D vision kit should do the trick. However, personally I only have
experiences with the "professional" NVidia quadro grafics card series.
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