Re: [ccp4bb]: selenocysteine in mad method...?

["U. A. Ramagopal" <acharya@lsx9b.nsls.bnl.gov>]

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	Hi Rajaram,

	Yes! you can solve the protein with selenocysteine. It is the
selenium atom from which you get the anomalous signal. I am assuming that
you are talking about the protein that naturally contains selenocysteine.
If so, how many selenocysteines you have in the protein(may be one)? How
big is the protein? and the quality of the diffraction matters for de
novo phasing by SAD or MAD methods.
If you can get good data you don't have to wait for synchrotron beam time
to do phasing (collect good redundant data with Cu Ka radiation in our
MBU X-ray data colection facility and SAD/SIRAS may work for 200 residue
protein with one selenium!!!).

 Also. see this paper (it is not a paper related to phasing with
selenocysteine, but interesting paper).

	S-SAD, Se-SAD and S/Se-SIRAS using Cu radiation: why wait for
synchrotron time?
	Lemke et al, Acta Cryst. 2002, D58, 2096-2101.


	Ramagopal


On Sat, 28 Dec 2002, Rajaram V wrote:

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>
>
> hi!
> i have joined this group today. this is my first mail.
>
> Has any structure be solved by MAD method using selenocysteine instead of
> selenomethionine? If so pls, send me any details regarding that.
> (references, name of the protein or any other information)
>
> hoping to get early replies
>
> regards
> Rajaram
>
>
>
>
>
>