[phenixbb] off-topic-Question

[Haytham Wahba]

  Dear all

i have protein soaked in Dimethyltindibromide

in the active site 2 cysteine and 1 aspartic acid

by help of anomalous map i can see 2 Sn atoms in each subunit in AU

there is difference in both subunits, Sub-A shows acetate near Sn
and Sub-B show phosphate ion, even the position of one of the 2 cystein is different from unit to other 
1-is it normal to see such difference between 2 subunit? 


also the distances between Sn and surrounding atoms does not suggest covalent binding

2-the important question is how to confirm if the 2 methyl groups or even one methyl group of dimethlytin are still there or cleaved

i mean one can not differentiate between density of water and methygroup.
How to define coordinate number of Heavy atom and identity of the attached atoms
as you will see in the link below (with water) and (with Methyl) the map are the same and as well r-factors

3-what can i do to confirm presence or cleavage of methyl: collect more data or using other technique like exafs, Mossbauer spectroscopy could help

(with water)

http://dl.dropbox.com/u/12001878/Subunit-A.png
 
http://dl.dropbox.com/u/12001878/subunit-A-anomalous.png
 
http://dl.dropbox.com/u/12001878/Subunit-B.png
 
http://dl.dropbox.com/u/12001878/subunit-B-anomalous.png
 
(with methyl)

 
http://dl.dropbox.com/u/12001878/DimethylTin-subunit-A-alt-conf.png
 
http://dl.dropbox.com/u/12001878/DimethylTin-subunit-B.png

N.B: resolution 1.7 A
r factors and molprop are perfect.


thank you for your time

haytham
biochimi
canada
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