2.5.1.11 - FIT atom_name1 atom_name2 ....
Pairwise Molecule FITTING. PLATON contains a FIT routine based on quaternion rotation
(Mackay, 1984). The general instruction to fit two molecules or residues is:
FIT At11 At21 At12 At22 .....(etc)
where atoms to be fitted are given pairwise.
Note: The FIT instruction may be broken up over more than one line. Lines that are to be
continued should end with '='.
There are two modes of operation:
1.
when specified before any CALC instruction, the actual calculation will be done
along with the subsequent CALC GEOM or CALC INTRA calculation. Listing of the
results will be on the
.lis file only.
2. when specified after a CALC INTRA or CALC GEOM calculations will be done directly.
Listing of the results of the calculation are both on the interactive output window and in the
listing file.
A PLUTON window is brought up with a display of the fit.
A special case is the situation where the two molecules to be fitted have similar numbering of the
atoms. The automatic sorting feature of PLATON will put the atoms in the same order. In such a
case, specification of only one atom from each of the molecules will be sufficient to fit all non-
hydrogen atoms in
both molecules
Example:
FIT O11 O21
In
the interactive mode, an automatic fit will be attempted with the specification of
two residue
numbers
Example:
FIT 1 2
2.5.2 – GEOMETRY CALCULATIONS
2.5.2.1 - CALC
The full range of molecular geometry calculations will be carried out automatically with a
the single keyword instruction CALC. This includes all the calculations that may be
executed alternatively with the instruction sequence CALL ADDSYM, CALC INTRA,
CALC INTER, CALC COORDN and CALC METAL, CALC SOLV, VALIDATION.
Appendix VI details the output.
Example:
CALC
2.5.2.2 - CALC INTRA (El1 r1 (El2 r2) (..)) (TOLA p1) (NOBOND) (NOANG) (NOTOR)
(NOLSPL) (NORING) (NOTMA) (NOBPA) (NOSTD) ((A/U/E)WLSPL) (NOPESD)
(NOMOVE) (NOSYMM) (TOLP p2) (TOLEA p3) (TOLM p4) (MAXDEV p5) (NOSORT)
The default instruction CALC INTRA produces a full calculation and listing of all intra-
molecular geometrical parameter options relevant for the structure at hand using default
covalent radii drawn from internal tables. Atoms with distances less than the sum of their
covalent radii plus a tolerance TOLA (Default = 0.4 Angstrom) are considered to be bonded.
The default radii values may be modified by explicit specification (in which case the default
as opposed to just the unique part.
Example:
CALC GEOM EUCLID EXPAND
2.5.2.4 - CALC TMA (Rmax[0.25]) (Atmin[7]) (HINCL) (CARTESIAN)
This invokes the execution of a rigid-body thermal motion analysis and the calculation of
derived quantities. It is automatically included in a CALC INTRA calculation. Note: No
TMA analysis is done when the residue contains too few atoms or when the R-index of the
observed and calculated Uij's is too high. (Rmax = 25 by default).
Example:
CALC TMA 0.30 8
2.5.2.5 - CALC INTER (El1 p1 El2 p2 ..)/(TOLR p1)
Short inter-molecular contacts are listed with this instruction. By default van der Waals radii
drawn from internal tables are used in conjunction with a default tolerance (TOLR = 0.2
Angstrom). Hydrogen bonds are automatically found and analyzed.
2.5.2.6 - CALC HBONDS (NONA) (DISORDER) (p1 p2 p3)
This instruction provides a subset of the information generated with
the CALC INTER instruction
and may be of use when interest is concentrated on H-bonds.
The parameters p1,p2 & p3 are the same as described for the HBOND directive.
Specification of the sub-keyword NONA will suppress the network analyses section of
the H-Bond
calculation.
The search for hydrogen bonds is by default done only for the full weight or major disorder atoms.
The sub-keyword DISORDER may be used to include minor disorder positions as well in the
analysis.
Example:
2.5.2.7 - CALC COORDN (p1/El1 r1 El2 r2 .. FIVE (TBA))(NOANG)
This instruction gives an analysis of the coordination sphere for the atom types specified
with El1 etc. Bond distances and bond angles are calculated for atoms within the specified
radii. By default (i.e. no specific options and data specified) such a calculation is done for
all atom types, excluding C and H, and with a radius of 3.6 Angstrom. This default radius
may be changed with the specification of the desired value p1. Alternatively a list of
selected elements and their corresponding coordination radii may be specified for the
coordination geometry calculations. Bond angles may be excluded from the listings with the
NOANG sub-keyword. A Berry pseudo rotation analysis is carried out automatically when
an atom is found to be bonded to exactly 5 atoms. Such a calculation may be enforced for
the five shortest contacts with the sub-keyword FIVE optionally followed with the value for
the Trans-basal-Angle (default TBA = 150 degree).
Example:
CALC COORDN 4.0 NOANG
Example:
CALC COORDN P 3.0 FIVE