Hello, I was wondering if the f'' determined by XANES experiment is quantitatively significant and if it can be contributed by two different anomalous scatterers. For example in my protein I know that Co and Zn are present. In theory, at Zn absorption edge, I have a contribution from Co too. If I perform a XANES experiment to determine Zn absorption edge and I obtain a f'' of 5.87, does this value correspond to only Zn signal or to a sum of Zn+Co? Thanks a lot Matteo -- Matteo Colombo PhD Groupe Extremophile et grands assemblages moléculaire Institut de Biologie Structurale 71 avenue des Martyrs CS 10090 38044 Grenoble Cedex 9
Dear Matteo, When you collect data at the Zinc K-edge, you will have a very small component of Co in the f'', since your protein as both Zn and Co. On the other hand, the f' will still have a significant contribution of both Zn and Co. I usually check Ethan's website and I am attaching a figure for the Zn, Co absorption edges: http://skuld.bmsc.washington.edu/scatter/AS_form.html Best regards, Joao Dr Joao Dias Principal Scientist Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, Herts, AL7 3AX UK This document contains company confidential and/or proprietary information. It is intended for the exclusive attention of the addressee(s) above and should not be copied or disclosed to any other. If you have received this transmission in error, please make no use of its contents and contact the sender. The information in this e-mail is confidential and may be legally privileged. It is intended for the exclusive attention of the addressee stated above and should not be copied or disclosed to any other. If you have received this transmission in error, please make no use of its contents and contact the sender. Contact and registered office address: Heptares Therapeutics Limited, BioPark, Broadwater Road, Welwyn Garden City, Hertfordshire, AL7 3AX. Company No: 06267989 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Matteo Colombo Sent: 20 October 2014 13:45 To: [email protected] Subject: [phenixbb] anomalous signal Hello, I was wondering if the f'' determined by XANES experiment is quantitatively significant and if it can be contributed by two different anomalous scatterers. For example in my protein I know that Co and Zn are present. In theory, at Zn absorption edge, I have a contribution from Co too. If I perform a XANES experiment to determine Zn absorption edge and I obtain a f'' of 5.87, does this value correspond to only Zn signal or to a sum of Zn+Co? Thanks a lot Matteo -- Matteo Colombo PhD Groupe Extremophile et grands assemblages moléculaire Institut de Biologie Structurale 71 avenue des Martyrs CS 10090 38044 Grenoble Cedex 9 _______________________________________________ phenixbb mailing list [email protected] http://phenix-online.org/mailman/listinfo/phenixbb
On Mon, Oct 20, 2014 at 6:48 AM, Joao Dias
When you collect data at the Zinc K-edge, you will have a very small component of Co in the f'', since your protein as both Zn and Co. On the other hand, the f' will still have a significant contribution of both Zn and Co.
I'm confused, isn't this backwards? Based on the plot, Co f'' will still be nearly 3e- at the Zn K-edge, but the f' will be close to zero. -Nat
Hi Nat,
You are correct, when you collect data at the Zinc K-edge, you will should expect Co f' nearly 0 and f'' nearly 3, and Zn f' -8 and f'' 4, respectively.
At the Zinc K-edge, f'' will have a significant contribution of both Zn and Co.
f' mainly have only the contribution of Zn (f'= -8) as Co will be nearly zero.
Thanks,
Joao
From: Nathaniel Echols
Hi Matteo, you are right, the absolute value contains the contribution from all absorbing elements. The edge can be determined reliably, though, because it is not shifted with respect to the energy (by this effect), only with respect to the amplitude. Best, Tim On 10/20/2014 02:44 PM, Matteo Colombo wrote:
Hello, I was wondering if the f'' determined by XANES experiment is quantitatively significant and if it can be contributed by two different anomalous scatterers.
For example in my protein I know that Co and Zn are present. In theory, at Zn absorption edge, I have a contribution from Co too. If I perform a XANES experiment to determine Zn absorption edge and I obtain a f'' of 5.87, does this value correspond to only Zn signal or to a sum of Zn+Co?
Thanks a lot
Matteo
-- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A
participants (4)
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Joao Dias -
Matteo Colombo -
Nathaniel Echols -
Tim Gruene