Well, trying to solve a MR structure with low homology (20%) and several
molecules is always a challenge...
Use any information you have.
How many molecules are possible/probable given the mol.wt and unit cell?
(Matthews coeff gives suggestions..) But remember solvent content can vary
from 30% to
I am interested to know the resolution on the basis that the better it diffracts, the lower the solvent content, generally. Have you tried Bernard Rupp's server which gives you probabilities for the No mols per AU, partly based on resolution? The LLGs look challenging - I've seen higher ones
mber 13, 2019 at 8:33 AM
To: "CCP4BB@JISCMAIL.AC.UK"
Subject: [ccp4bb] difficult molecular replacement solution
I have been working on a protein structure which has been hard to solve by
molecular replacement.
Unit cell: (60.6, 172.34, 196.42, 90, 90, 90)
Space group: P 21 21 2
Dear Rob,
Based on our experience with difficult MR cases, I recommend performing
refinement on the coordinates from MR (I prefer PHENIX simulated annealing for
this step). Then send the refined map - WITHOUT the model - to automated
building with density modification. The auto-built model may
Have you looked at a self-rotation function? Those can sometimes be very useful
in deciphering multiplicity.
On 2019-11-13 09:33, Robert S Phillips wrote:
I have been working on a protein structure which has been hard to solve by
molecular replacement.
Unit cell: (60.6, 172.34, 196.42, 90,
Hi Rob,
the answer to the question "how many molecules are in the ASU?" is only
available after satisfactory model building and refinement. The Phaser results
that you show indeed suggest 6 mols/ASU, but they don't prove it. If I were
you, I'd give the 6-molecule solution the highest priority,
Look at the chain packing in your solution. If the solution is grossly
correct you will notice nice solvent channels and no glaring chain-size
holes and no gross overlaps. The initial maps should look sensible, if
noisy.
If the protein is composed of likely dimers, try a search with dimer units
I have been working on a protein structure which has been hard to solve by
molecular replacement.
Unit cell: (60.6, 172.34, 196.42, 90, 90, 90)
Space group: P 21 21 21
The problem is that the homologues have only ~20% identity, and there are
multiple chains in the asymmetric unit. The
