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[ccp4bb]: Refmac5 refinement of residues having alternate locations



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Dear All,
The question is about Refmac5 refinement of residues having
alternate locations.
The input pdb file is like:

........
ATOM     50  O   GLY A   6     161.528  26.356 120.426  1.00  9.11   8
ATOM     51  N   LYS A   7     160.374  27.641 119.021  1.00  9.68   7
ATOM     52  CA  LYS A   7     160.767  28.872 119.659  1.00 11.39   6
ATOM     53  CB ALYS A   7     160.663  30.041 118.686  0.50 12.85   6
ATOM     54  CB BLYS A   7     160.683  30.038 118.701  0.50 12.85   6
ATOM     55  CG ALYS A   7     159.228  30.228 118.136  0.50 20.50   6
ATOM     56  CG BLYS A   7     161.638  29.910 117.525  0.50 20.50   6
ATOM     57  CD ALYS A   7     159.134  30.983 116.801  0.50 27.69   6
ATOM     58  CD BLYS A   7     161.417  31.016 116.509  0.50 27.69   6
ATOM     59  CE ALYS A   7     157.756  30.775 116.166  0.50 31.56   6
ATOM     60  CE BLYS A   7     162.153  30.728 115.210  0.50 31.56   6
ATOM     61  NZ ALYS A   7     157.377  31.895 115.260  0.50 34.80   7
ATOM     62  NZ BLYS A   7     161.539  31.436 114.054  0.50 34.80   7
ATOM     63  C   LYS A   7     159.836  29.082 120.876  1.00 11.28   6
ATOM     64  O   LYS A   7     158.964  28.253 121.142  1.00 10.30   8
ATOM     65  N   LEU A   8     160.021  30.172 121.607  1.00 10.71   7
........

after 3~5 cycles' refinemenit, the atoms of LYS7 went out of the
density (but other part of the structure looked OK) and the R-factor/
Free-R-factor increased.
5-fold NCS restraint (tight) for main chain and side chains was used.


Can anybody give me a suggestion?

Thanks a lot!
Xiaofeng Zhang


P.S.
side chain atoms at alternate locations are NCS-related.



-----------------------------------------------------------
Xiaofeng Zhang Ph.D. Student
Department of Bioscience
Karolinska Institute, NOVUM
141 57 Huddinge

Email: xiaofeng.zhang@biosci.ki.se
http://www.csb.ki.se/users/xray/xiaofeng/xiaofeng.html
Tel: +46-(0)8-6089177  Fax: +46-(0)8-6089290
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