Appendix 1: Symmetry Operations

The data type SymOP is used to succinctly describe crystallographic symmetry operations that may be performed on ATOM/HETATM coordinates. Symmetry operators applicable to a given entry are presented in REMARK 290. Each operator is assigned a serial number. The SymOP is a number of up to six (6) digits that indicates the serial number of the symmetry operator and the cell translations along the x, y, and z axes.

The SymOP data type is of the form nnnMMM where 'n' is the serial number of the symmetry operator, and 'MMM' is the concatenated cell translations along x, y, z with respect to the base number 555. Symmetry operators listed in REMARK 290 operate on orthogonal crystallographic coordinates that appear in the entry..

The FORTRAN I3 I3 format statement can be used to interpret nnnMMM.

As an example, the SymOP 2456 indicates that the second symmetry operation as listed in REMARK 290 is applied with translation of -1 on x, and +1 on z. A program will be made available shortly that converts SymOP data into transformations that operate in the coordinate frame used in the entry.

The SymOP data type is used in SSBOND, LINK, HYDBND, SLTBRG and REMARKs.

Template

1         2         3         4         5         6         7
1234567890123456789012345678901234567890123456789012345678901234567890
REMARK 290
REMARK 290 CRYSTALLOGRAPHIC SYMMETRY
REMARK 290 SYMMETRY OPERATORS FOR SPACE GROUP: P 21 21 21
REMARK 290
REMARK 290      SYMOP   SYMMETRY
REMARK 290     NNNMMM   OPERATOR
REMARK 290       1555   X,Y,Z
REMARK 290       2555   1/2-X,-Y,1/2+Z
REMARK 290       3555   -X,1/2+Y,1/2-Z
REMARK 290       4555   1/2+X,1/2-Y,-Z
REMARK 290
REMARK 290     WHERE NNN -> OPERATOR NUMBER
REMARK 290           MMM -> TRANSLATION VECTOR
REMARK 290
REMARK 290 CRYSTALLOGRAPHIC SYMMETRY TRANSFORMATIONS
REMARK 290 THE FOLLOWING TRANSFORMATIONS OPERATE ON THE ATOM/HETATM
REMARK 290 RECORDS IN THIS ENTRY TO PRODUCE CRYSTALLOGRAPHICALLY
REMARK 290 RELATED MOLECULES.
REMARK 290   SMTRY1   1  1.000000  0.000000  0.000000        0.00000
REMARK 290   SMTRY2   1  0.000000  1.000000  0.000000        0.00000
REMARK 290   SMTRY3   1  0.000000  0.000000  1.000000        0.00000
REMARK 290   SMTRY1   2 -1.000000  0.000000  0.000000       36.30027
REMARK 290   SMTRY2   2  0.000000 -1.000000  0.000000        0.00000
REMARK 290   SMTRY3   2  0.000000  0.000000  1.000000       59.50256
REMARK 290   SMTRY1   3 -1.000000  0.000000  0.000000        0.00000
REMARK 290   SMTRY2   3  0.000000  1.000000  0.000000       46.45545
REMARK 290   SMTRY3   3  0.000000  0.000000 -1.000000       59.50256
REMARK 290   SMTRY1   4  1.000000  0.000000  0.000000       36.30027
REMARK 290   SMTRY2   4  0.000000 -1.000000  0.000000       46.45545
REMARK 290   SMTRY3   4  0.000000  0.000000 -1.000000        0.00000
REMARK 290
REMARK 290 REMARK: NULL