mailRe: dimer


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Posted by Stefano Luciano Ciurli on June 10, 2014 - 13:39:
Hi Edward,
thinking about it, and considering that we erroneously run Relax using the 
full PDB for the homodimer but provided only the T1, T2 and NOE data for one 
monomer, as output of Dynamics Center, could you tell us how to modify the 
.txt files from Dynamics Center so that Relax "thinks" it has a full set of 
data for the full homodimer? The PDB that we used has residues already 
numbered consecutively from residue 1 to the last residue of the dimer.
We really need to change the input files for T1, T2 and NOE in order to 
decide which part of the protein we are looking at, but we would like to know 
which parts of the output files from DC should be duplicated. If you want and 
need it, I can send you the files in a private email to you only.
Looking forward to hearing from you
Stefano

On Jun 6, 2014, at 8:35 AM, Edward d'Auvergne wrote:

Hi Stefano,

It will be interesting to see the results in your final publication.
Especially considering that the relaxation data you observe is the
average of two states experiencing different global tumbling (the two
vectors intersect different parts of a single Brownian diffusion
tensor), but the assumption is made that they only sample one.  Maybe
you should perform a full analysis on one monomer, and then another
full analysis on the second, and compare.  Are you sure there are no
published theoretical treatments of such a situation?

As for the PyMOL or MOLMOL macros, I've had a look at the PDB file you
attached to http://gna.org/support/?3110, and this might be difficult.
Although both molecules are represented as different chains, the
residue numbers are not reset between the A to B transition:

"""
ATOM   2437  HE1 HIS A 147      14.544 -14.592  44.384  1.00142.09          
 H
ATOM   2438  C   HIS A 147      15.448 -12.825  50.108  1.00142.09          
 C
ATOM   2439  O   HIS A 147      16.622 -12.826  50.563  1.00142.09          
 O
ATOM   2440  OXT HIS A 147      14.601 -13.730  50.336  1.00142.09          
 O
TER    2441      HIS A 147
ATOM   2442  N   MET B 148      34.965   4.924 102.588  1.00 83.68          
 N
ATOM   2443  H   MET B 148      35.604   5.224 103.352  1.00 83.68          
 H
ATOM   2444  CA  MET B 148      33.567   5.117 103.004  1.00 83.68          
 C
"""

Do you have the ability to renumber residues?  This is rather simple
in relax, though not so obvious as it plays directly with the relax
data store object and uses Python programming:

"""
# Create a data pipe.
pipe.create('renumber', 'N-state')

# Load the original PDB as two molecules.
structure.read_pdb('BpUreE_apo_model_full.pdb')

# Renumber all residues of the second molecule directly in the
internal structural object.
for i in range(len(cdp.structure.structural_data[0].mol[1].res_num)):
   cdp.structure.structural_data[0].mol[1].res_num[i] -= 147

# Write out the renumbered structure as a PDB file.
structure.write_pdb('BpUreE_apo_renumbered.pdb', force=True)
"""

If the residues are all the same, then the PyMOL or MOLMOL macros
should apply to both structures.  I just had a look and the macros
from the model-free analysis apply to residue numbers:

http://www.nmr-relax.com/api/3.2/specific_analyses.model_free.pymol-pysrc.html#Pymol.classic_colour
http://www.nmr-relax.com/api/3.2/specific_analyses.model_free.molmol-pysrc.html#Molmol.classic_colour

Regards,

Edward



On 5 June 2014 23:32, Stefano Luciano Ciurli <stefano.ciurli@xxxxxxxx> 
wrote:
Hi Edward,
I reached the end of the calculation of our protein dimer, and everything 
went smooth. We used two fields, and tomorrow I am about to start 
collecting the third field data. I wonder how to make it so that the 
molmol or pymol macros used to visualize the various parameters along the 
protein backbone can be twisted so that these are applied to both monomers 
instead of just one.
Cheers,
Stefano




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