Re: [ccp4bb]: NCS with molecular replacement

[Laurence Pearl <l.pearl@icr.ac.uk>]

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Are you 100% certain that there is not an alternative cell assignment in
your reciprocal lattice ?
Particulalrly if the data is weak and/or low/medium resolution, it is
sometimes possible for automatic indexing programs to choose an incorrect
cell - C centred monoclinic lattices are amongst the most common such
missassignments.

Laurence Pearl

Jeff Taylor wrote:

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>
> Hello -
>
> I have a rather sticky molecular replacement problem and I'm looking for
> helpful ideas.  My protein crystallizes in the C2 space group, although
> homologs of this protein crystallize in P61.  I mention the P61 crystals
> because when I try a self rotation on the C2 data I get peaks on the
> Kappa=60, 120, and 180 sections which look just like those from the P61
> data.  The cell dimensions for the C2 crystal are large and from the
> Matthews number, I'm expecting at least 6 molecules in the asymmetric
> unit (whereas the P61 data has one molecule/asymm), and so the signal in
> a cross rotation search will be small.  Has anyone worked out a way to
> take advantage of a NCS in a molecular replacement search?
>
> Thank you,
>
> Jeff Taylor
> --
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> Dr. Jeffrey S. Taylor       Duke University Medical Center
> Department of Biochemistry  Box 3711, Nanaline Duke Bld
> Phone (919) 681-5266        Durham, NC 27710

--

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  Laurence H. Pearl

  Section of Structural Biology, Institute of Cancer Research
  Chester Beatty Laboratories,  237 Fulham Road
  London SW3 6JB, UK

  Phone +44-207-970 6045 : Secretary +44-207-970 6046
  FAX   +44-207-970 6051 : E-Mail l.pearl@icr.ac.uk
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