If you don't have crystals yet, you'll find getting it to crystallize is
your main problem.
Finding 111 sites should be feasible without other tricks than very
careful data collection (see below); if you have two or more copies in
the ASU, you may find you need to do what the ribosome guys did, namely
use other derivatives (e.g TaBr clusters) to locate your seleniums, and
then phase.
If your resolution is low, you definitely want to do 2- or 3-wavelength
MAD.
So yes, it's definitely feasible. If you have crystals...
von Delft, Inoue, et al. 'Structure of E. coli ketopantoate
hydroxymethyl transferase complexed with ketopantoate and Mg2+, solved
by locating 160 selenomethionine sites'. /Structure /11, no. 8 (2003):
985--996.
http://www.cell.com/structure/retrieve/pii/S0969212603001588
On 13/06/2012 03:55, Francis E Reyes wrote:
Do you have crystals?
Do they diffract? If so, to what resolution?
What resolution do you require to answer your biological question?
F
On Jun 12, 2012, at 7:46 PM, LISA<science...@gmail.com> wrote:
Hi all,
My work is to solve huge complex containing 4 different proteins and total
molecular weight is about 300 KD. I can purify the complex by co-expression
them in E.coli. This complex contains 8 protein A, 2 protein B and 1 protein C
and D. protein B and protein C have homology structures deposited in PDB
database. No homology structure available for protein A and D, which contribute
60% of the whole molecular weight for the complex.
Now I am trying to find a way to solve the phase of this complex. I am
thinking of use sad or mad with se-Met. There total 111 Met residues in this
complex. Is it possible to solve this complex by se-Met? Does someone have
experience to solve huge complex structure with se-met? It is also very welcome
for all the suggestion. Thank you.
All the best,
Lisa
