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Re: [ccp4bb]: X-ray absoprtion edges used for MAD]



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Jan Abendroth wrote:
 Hi Gordon,
 the compilations I have found concerning this topic:
 
 W. Hendrickson (1999)
 Maturation of MAD phasing for the determination of macromolecular
 structures.
 J Synchr Rad 6, 845-851
 
 C. Ogata (1998)
 MAD phasing grows up
 Nat Struct Biol Synchrotron suppl, 638-640.
 
 Regards
 Jan
 
> gwebster@caregroup.harvard.edu wrote:
> >
> > ***  For details on how to be removed from this list visit the  ***
> > ***    CCP4 home page http://www.dl.ac.uk/CCP/CCP4/main.html    ***
> >
> > Dear All
> >
> > I am hoping that somebody amongst you might be able to furnish me with some
> > information ...
> >
> > We have recently solved the structure of the PDZ1 domain of Na+/H+ exchanger
> > regulatory factor
> > using the dispersive signal from the LIII edge of Mercury (see Webster at
> > al. (2001) Acta Cryst D57,
> > 714-716 and our J. Mol. Biol. paper that is currently in press). We were
> > unable to obtain satisfactory
> > expression of our protein from selenomethionine auxotrophs and only obtained
> > a single mercury
> > derivative in spite of an extensive heavy atom screen from which the SIR
> > phases were insufficient
> > to solve the structure.
> >
> > In the end then, we decided to try a MAD experiment using our lone Mercury
> > derivative and obtained a
> > beautiful anomalous signal at three different wavelengths on beamline F2 at
> > CHESS. An analysis of our
> > data with SOLVE yielded excellent phases and a model consisting of over 80%
> > of the protein was built
> > by ARP/WARP in the first electron density map calculated with the new
> > phases.
> >
> > I was wondering whether anybody had done a survey of elements other than
> > Selenium that have been
> > successfully used for structure determination with MAD, since it seems that
> > a lot of time can be saved
> > if even a single, suitable heavy-atom derivative of a protein can be
> > obtained for such an experiment. I
> > know that there are plenty of tables of wavelengths and dispersive
> > differences for different elements, but
> > I would be very interested to see if anybody had compiled statistics for
> > which elements had actually
> > worked for MAD structure determinations. Such a survey might beneficially
> > bias our choice of which
> > heavy-atoms are worth screening first, especially if the biological
> > labelling of proteins is not an option
> > due to time constraints or technical problems at the level of expression
> > etc.
> >
> > With thanks, in anticipation of your assistance
> >
> > Gordon
> >
> > Gordon Webster
> > Division of Experimental Medicine
> > Beth Israel Deaconess Medical Center
> > Harvard Institutes of Medicine
> > Boston USA
> >
> > email: gwebster@caregroup.harvard.edu
> 
> --
> ------------------------------
> Jan Abendroth
> Institut fuer Biochemie
> Universitaet Koeln
> Zuelpicher Strasse 47
> D-50674 Koeln
> 
> Tel: +49-(0)221 470 6455 (Labor)
>                     6445 (Buero)
> Fax: +49-(0)221 470 5092

-- 
------------------------------
Jan Abendroth
Institut fuer Biochemie
Universitaet Koeln
Zuelpicher Strasse 47
D-50674 Koeln

Tel: +49-(0)221 470 6455 (Labor)
                    6445 (Buero)
Fax: +49-(0)221 470 5092