Marcus,
May I ask the following: assuming 8 A is obtained from a single
crystal on the home source, what diffraction limit would one expect
on the PX scanner?
Best regards,
Klaus
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Klaus Fütterer, Ph.D.
Reader in Structural Biology
Undergraduate Admissions
School of Biosciences P: +44-(0)-121-414 5895
University of Birmingham F: +44-(0)-121-414 5925
Edgbaston E: [email protected]
Birmingham, B15 2TT, UK W: www.biochemistry.bham.ac.uk/klaus/
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On 30 Sep 2010, at 10:44, Marcus Winter wrote:
This recent discussion does tend towards the ideal scenario: of
identifying ones
best-diffracting crystals... before embarking on the synchrotron trip.
The established Oxford Diffraction PX Scanner home laboratory
instrument can
therefore be most useful. This enables the direct X-ray screening
of individual
(putative) single crystal objects, in situ, in the (any SBS format)
crystallisation plate.
Yours sincerely,
Marcus Winter (Oxford Diffraction Ltd. – now Agilent Technologies)
-----Original Message-----
From: CCP4 bulletin board [mailto:[email protected]] On Behalf
Of Phil Jeffrey
Sent: 28 September 2010 19:20
To: [email protected]
Subject: Re: [ccp4bb] Lousy diffraction at home but fantastic at
the synchrotron?
Often this reflect crystal size - a small crystal in a big beam (or
one
with a long path in air) on a home source would see the small
diffraction signal drop below the noise level quite quickly - often at
the low resolution intensity dip that sits very approximately around 6
Angstrom. On a synchrotron source with a tight low-divergence beam
that
matches more closely the crystal dimensions that same crystal will
appear to do rather better.
Also one is more likely to expose the crystal longer (in terms of
total
photon numbers) at a synchrotron, which itself begets better signal/
noise.
Alternatively: everyone tries harder before synchrotron trips....
Phil Jeffrey
Princeton
On 9/28/10 1:27 PM, Francis E Reyes wrote:
> Hi all
>
> I'm interested in the scenario where crystals were screened at
home and
> gave lousy (say < 8-10A) but when illuminated with synchrotron
radiation
> gave reasonable diffraction ( > 3A) ? Why the discrepancy?
>
> Thanks
>
> F
