When I experienced strong difference density near methionines, It could be explained by an alternative conformation of the residue...
greetings, david
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Datum: Fri, 13 Apr 2007 09:51:09 -0000
Von: Ethayathulla Abdulsamath <[log in to unmask]>
An: [log in to unmask]
Betreff: [ccp4bb] Unusual Difference Fourier near Methionines
>
> Dear all
>
> I am doing one structure at 2.6A resolution where I found unusual density
> near methionines. Actually three methionines come close together nearby and
> I get difference even at 5sigma cutoff. I don't understand nature of the
> density. The amino acid sequnce is same I mean met by chemical sequncing so
> there is no change amino acid residues. I am sending the snapshot of the
> difference fourier observed at methionines. The crystal belong to R32 system
> with one molecule and biological trimer. In snapshot two of the methionines
> are symmetry related.
>
> Details of the data collection.
> Data collected at synchrotron
>
> Overall Rsym = 6 % and I/sigma = 2.1. Completeness = 99%
>
> Can anyone suggestion what could be chemical nature for the difference
> fourier.
>
> Thanks in advance
>
> Ethayathulla
>
> ###################################################
> A.S.Ethayathulla,Ph.D.
> Department of Biophysics
> All India Institute of Medical Sciences
> Ansari Nagar
> New Delhi-110029
> India.
> ###################################################
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