[phenixbb] molecular replacemnt problem
Appu kumar
appu.kumar9 at gmail.com
Sun Mar 24 03:26:06 PDT 2013
Dear members,
I am doing a molecular replacement of a
transcription factor whose ligand binding structure(24000 Da) is available
in PDB but not for the DNA binding(13000 Da). When i am searching for the
two copies from ligand binding domain as a template model, i am getting
very good solution but i am not getting any density for the DNA binding
domain to build up in density. The space gorup is P 1 21 1 (4) and unit
cell parameters are Unit Cell: 57.43 69.36 105.99 90.00 90.00
90.00. Please guide me how to get the complete model structure. Table below
show the matthews statistics
For estimated molecular weight 37000.
Nmol/asym Matthews Coeff %solvent P(2.20) P(tot)
_____________________________________________________________
1 5.71 78.46 0.00 0.01
2 2.85 56.91 0.62 0.70
3 1.90 35.37 0.37 0.29
4 1.43 13.82 0.00 0.00
_____________________________________________________________
The phaser molecular replacement gives the following table.
istogram of relative frequencies of VM values
----------------------------------------------
Frequency of most common VM value normalized to 1
VM values plotted in increments of 1/VM (0.02)
<--- relative frequency --->
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
| | | | | | | | | | |
10.00 -
8.33 -
7.14 -
6.25 -
5.56 -
5.00 -
4.55 -
4.17 -
3.85 --
3.57 ---
3.33 ------
3.12 ----------
2.94 **************** (COMPOSITION*1)
2.78 -----------------------
2.63 --------------------------------
2.50 -----------------------------------------
2.38 ------------------------------------------------
2.27 --------------------------------------------------
2.17 -----------------------------------------------
2.08 --------------------------------------
2.00 --------------------------
1.92 ---------------
1.85 -------
1.79 ---
1.72 -
1.67 -
1.61 -
1.56 -
1.52 -
1.47 * (COMPOSITION*2)
1.43 -
1.39 -
1.35 -
1.32 -
1.28 -
1.25 -
TABLE : Cell Content Analysis:
SCATTER
:N*Composition vs Probability:0|3x0|1:1,2:
$$
N*Composition Probability
$$ loggraph $$
1 0.306066
2 0.00141804
$$
Most probable VM for resolution = 2.27817
Most probable MW of protein in asu for resolution = 92664.2
I have initially indexed the data in C2221 but Rfree was not decreasing so
i reindexed the data in data in P121 space group keeping the Rfree flag of
C2221. While analysing the symmetry mates , i found large space but no
density. structure of Ligand binding domain is almost identical with 90%
identity in sequence. I am stuck with this problem and don't know how to
process further.
I run the phenix.xtriage to evaluate the twining but it suggest no twining.
When i reindex from C2221 to P21, the completeness of data reduced from 95
% to 35% whereas the map is very good and Rwork and Rfree are 26/31 for 2.2
resolution. I do not understand why the completeness of data reduced so
much on reindexing. please Can anyone explain this phenomenon.
Please give me your valuable suggestion. I will appreciate your effort.
Thank you
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