Hi Engin,
Two thoughts:
* Is the Patterson map consistent ? (with different resolution ranges,
exclusions, ...). You could possibly give 'GraphEnt' a try [assuming it
still works with current generation mtz files].
* The number of heavy atoms may be much larger and may deviate from
the known NCS (and, so, what you interpret as a self vector may not be a
self vector at all).
My twopence,
Nicholas
On Sun, 13 Sep 2009, Engin Ozkan wrote:
> Hi everybody,
>
> I have a little weekend puzzle in my hands. I have (probably) two heavy atom
> sites and pseudo-translation in P2(1) (i.e. an NCS 2-fold parallel to the
> unique crystallographic axis). Doing a little algebra, I would expect two self
> vectors and the pseudo-translation in the Harker section (y=0.5) of the
> Anomolous Difference Patterson map (plus a cross vector at y=0).
> Unfortunately, I am seeing only one of the self vectors and the vector
> corresponding to NCS+CS (pseudo-translation), but not the second self vector,
> which does not make sense to me. Drawing predicted pattersons confirms my
> expectations but not the real-world patterson map. I have already considered
> one site being weak as a possibility, but then the pseudo translation would
> not be stronger than the only self vector I'm seeing. I would appreciate
> anyone with a fresh brain pointing out what I might be missing here.
>
> Engin
>
> Anomalous Difference Patterson:
> CELL 95.4120 132.0710 99.0230 90.0000 109.0950 90.0000
> ATOM1 Ano 0.0000 0.0000 0.0000 53.95 0.0 BFAC 20.0
> ATOM2 Ano 0.4784 0.5000 0.0647 8.63 0.0 BFAC 20.0
> ATOM3 Ano 0.2043 0.5000 0.7631 7.23 0.0 BFAC 20.0
> ATOM4 Ano 0.1977 0.0000 0.1689 3.55 0.0 BFAC 20.0
> ATOM5 Ano 0.4099 0.5000 0.1794 3.01 0.0 BFAC 20.0
>
> Native Patterson:
> CELL 95.4120 132.0710 99.0230 90.0000 109.0950 90.0000
> ATOM1 Ano 0.0000 0.0000 0.0000 49.32 0.0 BFAC 20.0
> ATOM2 Ano 0.4686 0.5000 0.0465 8.99 0.0 BFAC 20.0
> ATOM3 Ano 0.5000 0.5000 0.9404 4.92 0.0 BFAC 20.0
> ATOM4 Ano 0.3074 0.0000 0.2447 3.49 0.0 BFAC 20.0
> ATOM5 Ano 0.1803 0.5000 0.7710 3.44 0.0 BFAC 20.0
> ATOM6 Ano 0.0479 0.0000 0.9072 3.35 0.0 BFAC 20.0
>
>
>
>
--
Dr Nicholas M. Glykos, Department of Molecular Biology
and Genetics, Democritus University of Thrace, University Campus,
Dragana, 68100 Alexandroupolis, Greece, Tel/Fax (office) +302551030620,
Ext.77620, Tel (lab) +302551030615, http://utopia.duth.gr/~glykos/
