The HETATM records present the atomic coordinate records for atoms within "non-standard" groups. These records are used for water molecules and atoms presented in HET groups.

Record Format

 1 -  6        Record name     "HETATM"

 7 - 11        Integer         serial         Atom serial number.

13 - 16        Atom            name           Atom name.

17             Character       altLoc         Alternate location indicator.

18 - 20        Residue name    resName        Residue name.

22             Character       chainID        Chain identifier.

23 - 26        Integer         resSeq         Residue sequence number.

27             AChar           iCode          Code for insertion of residues.

31 - 38        Real(8.3)       x              Orthogonal coordinates for X.

39 - 46        Real(8.3)       y              Orthogonal coordinates for Y.

47 - 54        Real(8.3)       z              Orthogonal coordinates for Z.

55 - 60        Real(6.2)       occupancy      Occupancy.

61 - 66        Real(6.2)       tempFactor     Temperature factor.

73 - 76        LString(4)      segID          Segment identifier;

77 - 78        LString(2)      element        Element symbol; right-justified.

79 - 80        LString(2)      charge         Charge on the atom.


* The x, y, z coordinates are in Angstrom units.

* Disordered solvents may be represented by the residue name DIS.

* No ordering is specified for polysaccharides.

* See the HET section of this document regarding naming of heterogens. See the HET dictionary for residue names, formulas, and CONECT records of the HET groups that have appeared so far in the PDB.

* For atoms that are in alternate sites indicated by the alternate site indicator, sorting of atoms in the ATOM/HETATM list uses the following general rules:

- In the simple case that involves a few atoms or a few residues with alternate sites, the coordinates occur one after the other in the entry.
- In the case of a whole macromolecular chain, or significant portion of a chain, having alternate sites, the atoms for each alternate position are listed together. The two conformers are delineated by MODEL/ENDMDL records. In this case each MODEL must represent the entire molecular assemblage, including any heterogen group which is not necessarily disordered. Such is the case when DNA molecules are placed in UP and DOWN positions.
- In the case of a large heterogen groups which are disordered, the atoms for each conformer are listed together. The two lists are not separated by MODEL/ENDMDL as is done for macromolecular chains.

* If the depositor provides the data, then the isotropic B value is given for the temperature factor.

* If there is no isotropic B value from the depositor, but there is an ANISOU record with anisotropic temperature factors, then the B equivalent is stored in the tempFactor field, as calculated by:

B(eq) = 8pi**2{1/3[U(1,1) + U(2,2) + U(3,3)]}
- This will obviate the need to check if ANISOU records are present before interpreting the contents of the temperature factor field.
- In some previously released PDB entries with anisotropic temperature factors provided as ANISOU records, the temperature factor field of the corresponding ATOM or HETATM record contained the equivalent U-isotropic [U(eq)] which is calculated by:
U(eq) = 1/3[U(1,1) + U(2,2) + U(3,3)] x 10**-4

* If there are neither isotropic B values from the depositor, nor anisotropic temperature factors in ANISOU, then the default value of 0.0 is used for the temperature factor.

* In some entries, the occupancy and temperature factor fields are often used for other quantities. In these cases, an explanation is provided in the remarks.

* Insertion codes, segment id, and element naming are fully described in the ATOM section of this document.

Verification/Validation/Value Authority Control

PDB processing programs check ATOM/HETATM records for PDB format, sequence information, and packing. The PDB reserves the right to return deposited coordinates to the author for transformation into PDB format.

Relationships to Other Record Types

HETATM records must have corresponding HET, HETNAM, FORMUL and CONECT records, except for waters.


         1         2         3         4         5         6         7         8
HETATM 1357 MG    MG   168       4.669  34.118  19.123  1.00  3.16          MG2+
HETATM 3835 FE   HEM     1      17.140   3.115  15.066  1.00 14.14          FE3+