Hi All,
Sorry for a non CCP4 querry.
 I am using CNS for composite omit map calculations. the structure is having
a ligand for which parameter and topology files have been generated using
PRODRG server. however while running composite_omit_map.inp i m getting the
following torsion topology error (where chain D is the ligand):


"ERROR: There are no suitable base groups.
   This problem can be caused by isolated
   bonding networks with undefined or weak
   dihedral force constants.
   The atoms that cannot be placed in a tree
   are listed below:
    %atoms "D   "-242 -AMG -O4
    %atoms "D   "-242 -AMG -C4
    %atoms "D   "-242 -AMG -C3
    %atoms "D   "-242 -AMG -O3
    %atoms "D   "-242 -AMG -C2
    %atoms "D   "-242 -AMG -O2
    %atoms "D   "-242 -AMG -C1
    %atoms "D   "-242 -AMG -O1
    %atoms "D   "-242 -AMG -C7
    %atoms "D   "-242 -AMG -O5
    %atoms "D   "-242 -AMG -C5
    %atoms "D   "-242 -AMG -C6
    %atoms "D   "-242 -AMG -O6
 %TORSION:TOPOLOGY error encountered: Fatal Topology Error
   (CNS is in mode: SET ABORT=NORMal END)
 *****************************************************
 ABORT mode will terminate program execution.
 *****************************************************
 Program will stop immediately."



topology and parameter files have been attached to this posting.

Kindly suggest if there is any problem with topology or parameter file or i
am missing on something else.

with best regards

Vineet Gaur

Attachment: mam.param
Description: Binary data

Attachment: mam.top
Description: Binary data

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