Their web page indicates they’re running a 315, so there are limits on useful low dose data collection. If you can get to a beamline with a pixel array detector and mount your samples carefully you’ll probably get more from low dose methods.
The key thing with this is minimising background from loop, drop etc so the photons you measure are as far as possible from the sample under study. You’ll probably benefit from combining data from multiple samples if they are isomorphous.
Obviously your ultimate resolution will be limited by the number of photons your sample can scatter before suffering measurable damage... but combining samples can help you here
Best wishes Graeme
On 29 Aug 2019, at 19:07, Kimberly Stanek <[log in to unmask]<mailto:[log in to unmask]>> wrote:
ALS 822. I tried as low as 0.2 sec exposure but it didn't seem to help much.
Kimberly Stanek
Postdoctoral Researcher, Goulding Lab
Co-chair, UCI Postdoctoral Association
University of California, Irvine
Natural Science I, Room 2302
(949) 824-0014
________________________________
From: James Holton <[log in to unmask]<mailto:[log in to unmask]>>
Sent: Thursday, August 29, 2019 10:50 AM
To: Kimberly Stanek <[log in to unmask]<mailto:[log in to unmask]>>; [log in to unmask]<mailto:[log in to unmask]> <[log in to unmask]<mailto:[log in to unmask]>>
Subject: Re: [ccp4bb] Semet derivative dying almost immediately in beam
What exposure time are you using? And which beamline?
-James Holton
MAD Scientist
On 8/29/2019 10:26 AM, Kimberly Stanek wrote:
Hi folks,
We have a protein that we have been trying to solve the structure of for a while now but so far haven't been able to get any diffraction better than ~4.5A. I was able to collect a full 360 degrees of data and index, but MR is failing so we have turned to de novo phasing.
Recently we prepared crystals of the Semet derivative under the same condition. While these crystals diffracted to about the same resolution, I found they were dying after just one or two snaps, even with increased beam attenuation and decreased exposure time. I am wondering if anyone has experienced anything like this before and had any suggestions on what to do about it.
Thank you,
Kimberly Stanek
Postdoctoral Researcher, Goulding Lab
Co-chair, UCI Postdoctoral Association
University of California, Irvine
Natural Science I, Room 2302
(949) 824-0014
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