haytham_wahba at yahoo.com
Thu Jul 14 11:26:22 PDT 2011
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
N.B: resolution 1.7 A
r factors and molprop are perfect.
thank you for your time
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