Are the Cys residues in question on the surface of the protein? DMSO
(which is in the crystallization mix) is a weak oxidant and could
conceivably contain impurities like dimethylsulfide and methanethiol
which could form difulfides with surface Cys residues. Or there could
have been sulfides carried over from the protein extraction and
purification steps. Does -S-S-CH3 fit the density with correct geometry?
_______________________________________
Roger S. Rowlett
Gordon & Dorothy Kline Professor
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
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On 5/13/2015 9:49 AM, Bio Physics wrote:
Is there any reason to be S-S-CH3 modification of a specific CYS!
Others CYSs are fine.
On Tue, May 12, 2015 at 5:27 PM, Finke Aaron (PSI) <[email protected]
<mailto:[email protected]>> wrote:
What are the bond lengths- or, rather, the centers from blob to
blob? Looks a bit short to be S-O, could be S-S-CH3?
Cheers,
Aaron
------------------------------------------
Dr. Aaron Finke
Postdoctoral Fellow
Swiss Light Source
WSLA/217
CH-5232 Villigen-PSI
phone: +41 56 310 5652 <tel:%2B41%2056%20310%205652>
e-mail: [email protected] <mailto:[email protected]>
On May 13, 2015, at 0:15, Bio Physics <[email protected]
<mailto:[email protected]>> wrote:
No, it is not sulfenic acid or so, I had that in differend
structure. It is L shaped from S, and linear if I put SCX mutaion
(another 1.4A way a nice blob). My resolution is 1.3 A.
On Tue, May 12, 2015 at 4:18 PM, Artem Evdokimov
<[email protected] <mailto:[email protected]>> wrote:
Looks like a wrong shape for tetrahedral acid
...
On May 12, 2015 4:07 PM, "Boaz Shaanan" <[email protected]
<mailto:[email protected]>> wrote:
Hi,
As I've just written to David, maybe it's sulfenic acid
(result of radiation damage?). I've had those in some
cases. See attached scheme for the chemistry and other
possibilities for Cys modification by oxidation.
Boaz
/Boaz Shaanan, Ph.D.
Dept. of Life Sciences
Ben-Gurion University of the Negev
Beer-Sheva 84105
Israel
E-mail: [email protected] <mailto:[email protected]>
Phone: 972-8-647-2220 Skype: boaz.shaanan
Fax: 972-8-647-2992 or 972-8-646-1710 /
//
//
/
/
------------------------------------------------------------------------
*From:* CCP4 bulletin board [[email protected]
<mailto:[email protected]>] on behalf of Bio Physics
[[email protected]
<mailto:[email protected]>]
*Sent:* Tuesday, May 12, 2015 11:57 PM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [ccp4bb] CYS mod
Hi All,
I have same type of modified CYS !!!
No BME.
On Tue, May 12, 2015 at 2:59 PM, David Schuller
<[email protected] <mailto:[email protected]>> wrote:
So far almost everyone is suggesting BME.
I didn't do the purification & crystallization
myself, but I am told:
Buffer was HEPES
cryo was ethylene glycol, glycerol and DMSO.
Some MgSO4 and KPO4
No BME, but maybe some DTT.
Purified from a proteobacterium.
On 05/12/15 15:20, Dyda wrote:
What is in buffer? Perhaps DTT and cacodylate?
Fred
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David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
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