R: Write PQR Format Coordinate File

write.pqr {bio3d} | R Documentation

## Write PQR Format Coordinate File

### Description

Write a PQR file for a given ‘xyz’ Cartesian coordinate vector or matrix.

### Usage

    write.pqr(pdb = NULL, xyz = pdb$xyz, resno = NULL, resid = NULL, eleno =
    NULL, elety = NULL, chain = NULL, o = NULL, b = NULL,
    append = FALSE, verbose = FALSE, chainter = FALSE, file = "R.pdb")

### Arguments

`pdb` | a PDB structure object obtained from `read.pdb` or `read.pqr`.
`xyz` | Cartesian coordinates as a vector or 3xN matrix.
`resno` | vector of residue numbers of length equal to length(xyz)/3.
`resid` | vector of residue types/ids of length equal to length(xyz)/3.
`eleno` | vector of element/atom numbers of length equal to length(xyz)/3.
`elety` | vector of element/atom types of length equal to length(xyz)/3.
`chain` | vector of chain identifiers with length equal to length(xyz)/3.
`o` | atomic partial charge values of length equal to length(xyz)/3.
`b` | atomic radii values of length equal to length(xyz)/3.
`append` | logical, if TRUE output is appended to the bottom of an existing file (used primarly for writing multi-model files).
`verbose` | logical, if TRUE progress details are printed.
`chainter` | logical, if TRUE a TER line is inserted between chains.
`file` | the output file name.

### Details

PQR file format is basically the same as PDB format except for the fields of `o` and `b`. In PDB, these two fields are filled with ‘Occupancy’ and ‘B-factor’ values, respectively, with each field 6-column long. In PQR, they are atomic ‘partial charge’ and ‘radii’ values, respectively, with each field 8-column long.

Only the `xyz` argument is strictly required. Other arguments assume a default poly-ALA C-alpha structure with a blank chain id, atomic charge values of 0.00 and atomic radii equal to 1.00.

If the input argument `xyz` is a matrix then each row is assumed to be a different structure/frame to be written to a “multimodel” PDB file, with frames separated by “END” records.

### Value

Called for its effect.

### Note

Check that: (1) `chain` is one character long e.g. “A”, and (2) `resno` and `eleno` do not exceed “9999”.

### Author(s)

Barry Grant with contributions from Joao Martins.

### References

Grant, B.J. et al. (2006) Bioinformatics 22, 2695–2696.

For a description of PDB format (version3.3) see:
http://www.wwpdb.org/documentation/format33/v3.3.html.

### See Also

`read.pqr`, `read.pdb`, `write.pdb`, `read.dcd`, `read.fasta.pdb`, `read.fasta`

### Examples

    # PDB server connection required - testing excluded

    # Read a PDB file
    pdb <- read.pdb( "1bg2" )

    # Write out in PQR format
    outfile = file.path(tempdir(), "eg.pqr")
    write.pqr(pdb=pdb, file = outfile)

    invisible( cat("\nSee the output file:", outfile, sep = "\n") )

[Package bio3d version 2.3-3 Index]