Dear all,
Thanks for all the advices. The solution worked for me is to
calculate Se-MAD phase and Hg-SIR (use SeMet remote wavelength as
"native") phase separately in SHARP; then combine the phase using CNS
(combine.inp). After density modification in DM, ~2/3 of one molecule
(4 molecules per ASU) can be traced. Then this molecule was used as a
search model for molecular replacement into the native data set using
Phaser. The resulting phase was very good so that most of the rest
model building was done with ARP. It appears phase combination is the
key for my case. I got multiple advices for crystal averaging and I
am sure it will be very powerful, although I have not got a chance to
try that yet.
Best regards,
Junyu
On Jul 17, 2008, at 11:13 AM, Junyu Xiao wrote:
Hi,
I have a very good native data set. However, the selenomethionyl
crystal has a different space group and always suffers from
radiation damage. A three-wavelength data set was still collected,
and after phasing in SHARP, some features can be seen but the map
is not good enough for tracing. Then I did some heavy atom soaking
with the native crystals and collected data at home, however, the
crystal was again converted into the same space group as the
selenomethionyl crystal. At lease 4 Hg sites can be found both by
isomorphous difference Fourier calculated using the partial Se-MAD
phase and by isomorphous difference Patterson, suggesting they
should be real. Now with these information, what's the best way to
do the phasing in SHARP, or in some other programs?
I hope I have made myself clear; and I would like to supply more
details. Any suggestion will be highly appreciated.
Best regards,
Junyu
==============================
Junyu Xiao
Department of Biological Chemistry,
University of Michigan
Lab address:
3163 Life Sciences Institute
University of Michigan
210 Washtenaw Avenue
Ann Arbor, MI, 48109-2216
Phone: 734-615-2078
==============================
==============================
Junyu Xiao
Department of Biological Chemistry,
University of Michigan
Lab address:
3163 Life Sciences Institute
University of Michigan
210 Washtenaw Avenue
Ann Arbor, MI, 48109-2216
Phone: 734-615-2078
==============================
