Index

Macromolecular dictionary (mmCIF) version 2.0.09

Category GEOM_TORSION

Name:
'geom_torsion'

Description:

   Data items in the GEOM_TORSION category record details about
   torsion angles as calculated from the
   contents of the ATOM, CELL and SYMMETRY data.

   The vector direction _geom_torsion.atom_site_id_2 to
   _geom_torsion.atom_site_id_3 is the viewing direction, and the
   torsion angle is the angle of twist required to superimpose the
   projection of the vector between site 2 and site 1 onto the
   projection of the vector between site 3 and site 4. Clockwise
   torsions are positive, anticlockwise torsions are negative.

   Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521-523.

Example:

Example 1 - based on data set CLPHO6 of Ferguson, Ruhl, McKervey & Browne [Acta Cryst. (1992), C48, 2262-2264].
 
    loop_
    _geom_torsion.atom_site_id_1
    _geom_torsion.atom_site_id_2
    _geom_torsion.atom_site_id_3
    _geom_torsion.atom_site_id_4
    _geom_torsion.value
    _geom_torsion.site_symmetry_1
    _geom_torsion.site_symmetry_2
    _geom_torsion.site_symmetry_3
    _geom_torsion.site_symmetry_4
    _geom_torsion.publ_flag
     C(9)   O(2)    C(7)    C(2)     71.8  .  .  .  .      yes
     C(7)   O(2)    C(9)    C(10)  -168.0  .  .  .  2_666  yes
     C(10)  O(3)    C(8)    C(6)   -167.7  .  .  .  .      yes
     C(8)   O(3)    C(10)   C(9)    -69.7  .  .  .  2_666  yes
     O(1)   C(1)    C(2)    C(3)   -179.5  .  .  .  .      no
     O(1)   C(1)    C(2)    C(7)     -0.6  .  .  .  .      no



Category groups:
    inclusive_group
    geom_group
Category keys:
    _geom_torsion.atom_site_id_1
    _geom_torsion.atom_site_id_2
    _geom_torsion.atom_site_id_3
    _geom_torsion.atom_site_id_4
    _geom_torsion.site_symmetry_1
    _geom_torsion.site_symmetry_2
    _geom_torsion.site_symmetry_3
    _geom_torsion.site_symmetry_4

Mandatory category: no