. Does any body else want to chime in?
Jim
-Original Message-
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of
Matthias Zebisch
Sent: Wednesday, November 11, 2009 6:16 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] sulfur sad phasing
Dear bb!
What
Dear bb!
What is the optimal wavelength for Sulfur SAD phasing?
Is it 1.9A or should one go below that to reduce absorption/damage.
Also, would the same wavelength be appropriate to maximize anomalous
scattering to position chlorides, calcium, sulfate in already phased
structures?
Thanks in
Hi Mattias,
For maximizing the anomalous scattering of chlorides, calcium and
sulfate I always collect highly redundant data (say 7 fold) at 7keV
(1.77A). As for the optimal wavelength for S-SAD I would point you to
the following publication:
Matthias Zebisch wrote:
Dear bb!
What is the optimal wavelength for Sulfur SAD phasing?
Is it 1.9A or should one go below that to reduce absorption/damage.
Also, would the same wavelength be appropriate to maximize anomalous
scattering to position chlorides, calcium, sulfate in already phased
Le 11 nov. 09 à 13:16, Matthias Zebisch a écrit :
Dear bb!
What is the optimal wavelength for Sulfur SAD phasing?
Is it 1.9A or should one go below that to reduce absorption/damage.
Also, would the same wavelength be appropriate to maximize anomalous
scattering to position chlorides, calcium,
Hi Matthias
Another crucial point to phase with sulphur anomalous signal is to use
an appropriate scaling protocol. You can find extense discussion in
the reference Matt posted.
In case you want just to calculate an anomalous difference Fourier map
you don't need to go that soft, you can
Miguel Ortiz Lombardia wrote:
Of course, as Fred said, the precission of the measurements is
extremely important for sulfur-SAD phasing.
What I was really meaning is the combination of i) accuracy and ii)
sufficient redundancy. Not too much, in your case, as you rightly say in
your mail.
Le 11 nov. 09 à 14:26, Jürgen Bosch a écrit :
Dear CCP4 community,
(hijacking the thread)
I so far failed to get a sulfur SAD phased structure and I blamed it
on the low symmetry space group C2 plus weakish diffraction if you
don't want to overexpose your crystal and be able to collect
Dear CCP4 community,
(hijacking the thread)
I so far failed to get a sulfur SAD phased structure and I blamed it
on the low symmetry space group C2 plus weakish diffraction if you
don't want to overexpose your crystal and be able to collect 20-30x
redundancy.
What do the expert think about
-
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of
Matthias Zebisch
Sent: Wednesday, November 11, 2009 6:16 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] sulfur sad phasing
Dear bb!
What is the optimal wavelength for Sulfur SAD phasing?
Is it 1.9A or should one go below
Hi Matthias,
S-SAD seems to require really strong diffraction, high symmetry, and
high data redundancy. In the end, the S ano signal is pretty weak even
at longer wavelength. While S-SAD might work, Iodide soaks might be a
much more practical approach. Iodide has some 6 electrons at CuKa.
want to chime in?
Jim
-Original Message-
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of
Matthias Zebisch
Sent: Wednesday, November 11, 2009 6:16 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] sulfur sad phasing
Dear bb!
What is the optimal wavelength for Sulfur SAD
On 13:16 Wed 11 Nov , Matthias Zebisch wrote:
What is the optimal wavelength for Sulfur SAD phasing?
Is it 1.9A or should one go below that to reduce absorption/damage.
Some additional advice about factors other than wavelength: For S-SAD on
a home Cu source, my previous lab showed that
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