On Mar 15 2007, Yi Xue wrote:
So far, the native crystals diffracted best to 2.4A. The MAD data
diffracted to 2.6~2.7A. We attempted to use phenix.hyss to identify copper
atoms, and the program had hard time to identify the sites.
The protein: Cu ratio is around 1:1, which is decided by ICP-A
I personally have had problems solving structures with large copy #s in
the asymmetric unit despite a good model (my failure occurred at 14 in
the a/u in primitive orthorhombic) - at the time finding the first
monomer proved to be impossible. This was also a structure in which the
systematic a
There are no easy answers for difficult problems, but have a look at
A. Gonzalez, J. Synchrotron Rad. (2007). 14, 43-50
Hopefully some of the tips given there can help in your case.
On Thu, 15 Mar 2007, Yi Xue wrote:
YX > Thus, basically, the Cu anomallous signal is very weak, and the
YX >c
Hi
For your SAD / MAD data, firstly after merging can you see any peaks in the
anomolous difference patterson map - this is critical. You could try using
SOLVE / RESOLVE or SHARP / AUTOSHARP to identify sites and to calculate phases,
as you have a little bit more control over the process. You
So far, the native crystals diffracted best to 2.4A. The MAD data
diffracted to 2.6~2.7A. We attempted to use phenix.hyss to identify copper
atoms, and the program had hard time to identify the sites.
The protein: Cu ratio is around 1:1, which is decided by ICP-AES measurement
of the crystalliza
It would be useful to know how you tried to solve the structure by MR.
Just because there is a large number of chains in the ASU isn't a reason
that MR will fail. At times you need to find some of the chains, do some
rebuilding, and then use that amended model for a continued search.
Bernie Santar
Hi:
Is the resolution of the data sufficient to apply direct methods to find
only the copper atoms, then use the copper atom positions in an
old-fashioned
'heavy-atom' phasing method, combined with direct methods?
Incidentally, was the following publication of any relevance in your
effort
Dear all:
We already got nice crystals of a drug-protein complex, however, MR
failed due to the huge copies (>12) of protein molecules per asu. Protein
itself is a small one, only ~70 aa.
Later on, we collected MAD data of copper (copper : protein ~ 1: 1),
Rsym of the data was around ~9%
