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
--
Engin Özkan
Post-doctoral Scholar
Howard Hughes Medical Institute
Dept of Molecular and Cellular Physiology
279 Campus Drive, Beckman Center B173
Stanford School of Medicine
Stanford, CA 94305
ph: (650)-498-7111
