DECaF - Diffuse: Extract & Calculate F²

A Python package for extracting and simulating diffuse scattering of X-rays in protein crystals

How to cite

If you use this software, please cite the following paper: TBC

Requirements

• phenix/cctbx: runs in cctbx.python (2.7.x / 3.x) and depends on cctbx modules
• dials/dxtbx: used for reading crystallographic image files
• numpy
• scipy
• matplotlib

Usage

Make sure cctbx.python is available and the dxtbx package is installed.

Clone the repository

git clone https://github.com/jvdhorn/decaf

Update PATH and PYTHONPATH

source source_env.sh

Optional: install package

cctbx.python -m pip install .

Command-line parameters can be provided using Phil syntax. For example:

schimpy pdb_in=structure.pdb tls_in=optimised_model.json

Run any of the modules without arguments to get an overview of the available parameters for that module.

Overview of modules

• schimpy - SuperCell Hierarchical Model
• stimpy - Statistical Image-processing
• slicemtz - Viewing utility for mtz-file
• submtz - Subtract two mtz-files
• plotmtz - Plot intensity distributions in mtz-files
• ccmtz - Calculate correlation coefficient and R1-values between mtz-files
• rmbragg - Remove supercell voxels around Bragg positions in mtz-file
• mtzstats - Show various statistics including R-int for mtz-file
• stimpy3d - Apply the stimpy-procedure to resolution bins in mtz-file
• patterson - Calculate Patterson map from mtz-file
• pattsize - Estimate the size of the Patterson origin-peak
• mtz2txt - Extract raw intensities from mtz-file
• mtz2map - Convert mtz to ccp4 map-file
• map2mtz - Convert ccp4 map-file to mtz
• filter_mtz - Apply a kernel-filter to an mtz-file
• qdep - Find power law for intensity decay around Bragg positions in mtz-file
• pdbrad - Estimate the size of a pdb-object
• pdbdist - Plot C-alpha distance stdev matrix for multistate pdb
• btrace - Plot C-alpha B-factor trace

Most important command-line parameters

schimpy

• pdb_in - refined structure file (pdb)
• tls_in - result of the ECHT B-factor distribution (json)
  • if not provided, TLS-matrices are extracted from pdb_in (if available)
• sc_size - size of the supercell (e.g. "5 5 10")
• correlate - enable or disable correlation of TLS-groups (default True)
• stretch - stretch parameter for the anchor points (default 0.25)
• cutoff - distance cutoff for intermolecular interactions (default 3.0)
• weights - power for the number of interactions (default 1.5)
• max_level - highest level of the TLS-hierarchy to include (default 1)
• resolution - resolution limit (default 2.0)
• k_sol and b_sol - bulk solvent parameters (default 0.35 and 50.0)
• tls_multipliers - multipliers for all input tls matrices (e.g. "1.0 0.0 0.0")
• skip - skip correlation (but not displacements!) for these levels (e.g. "2 3 4")
• reverse - start procedure at highest level of the hierarchy (default True)
• swap_frac - end correlation prematurely after this fraction of swaps (default 1.0)
• energy_percentile - only allow swaps for which local energy exceeds this percentile (default 0.0)
• processes - number of parallel simulations (default 1, watch memory usage!)
• interval - number of seconds between consecutive simulations (default 1.0)
• n_models - number of supercells to simulate (default 128)

stimpy

• image - raw image file
• radial - polarization-corrected radial average
• bin_counts - bin regions within this range of counts (default 1.0)
• N - expected number of independent rotations (default 1.0)
• median_size - kernel size of the median filter (default 9)
• dilation_size - kernel size of the mask dilation (default 5)

slicemtz

• mtz - input mtz or map-file
• lbl - array of interest (default IDFF)
• slice - desired slice to plot (default hk0)
• save - save image as high-res PNG instead of plotting (default False)
• depth - additional depth of the slice on both sides (default 0)
• sc_size - size of the supercell for drawing Bragg positions (e.g. "5 5 10")
• log - plot log10 of the intensities (default False)
• min and max - minimum and maximum values to plot
• autoscale - decrease upper bound for more detail in skewed slices (default True)
• zoom - zoom in around a given coordinate ("[x] [y] [pad]", e.g. "65 65 27")
• inset - inset zoom around a given coordinate ("[x] [y] [pad]", e.g. "65 65 27")
• contours - plot this many contours instead of raw values (e.g. 127)
• projection - construct a cylindrical projection (gp, eq or mercator)
• center - shift grid to put the corner in the center (default False)

submtz

• mtz_1 - first input mtz-file
• mtz_2 - second input mtz-file (can be multiple)
• lbl_1 - first array of interest (default IDFF)
• lbl_2 - second array of interest (default IDFF)
• mode - use a different operator (sub, add, mul, div or merge, default sub)
• scale - scale factor for second mtz-file (0 for autoscale, default 1.0)

plotmtz

• mtz - input mtz-file (can be multiple)
• lbl - array of interest (default IDFF)
• log - plot logarithmic distributions (default True)
• resolution - low and high resolution (e.g. "3.6 3.4")

ccmtz

• mtz_1 - first input mtz-file
• mtz_2 - second input mtz-file
• lbl_1 - first array of interest (default IDFF)
• lbl_2 - second array of interest (default IDFF)
• bins - number of resolution shells (default 10)
• hlim and klim and llim - limit h, k, and l (e.g. "-20 20")
• resolution - low and high resolution (e.g. "3.6 3.4")

rmbragg

• mtz - input mtz-file
• sc_size - supercell size (e.g. "5 5 10")
• box - number of voxels to remove around every Bragg position (default "1 1 1")
• fraction - remove this fraction of highest intensities in every box (e.g. 0.05)
• subtract - subtract common intensities in resolution shells (mean or min)
• keep - invert selection (default False)

mtzstats

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• sg - space group for R-int (symbol or number, e.g. P43212 or 96)
• resolution - low and high resolution (e.g. "3.6 3.4")

stimpy3d

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• bins - number of resolution shells (default 1)
• N - expected number of independent rotations (default 1.0)

patterson

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• bins - divide into this many shells and subtract the mean from each one (e.g. 50)
• sample - sampling of the grid in 1/Angstrom, higher is finer (default 3.0)
• use_intensities - calculate Patterson using intensities instead of F (default False)
• center - place the origin in the center of the map (default True)
• limit - real space limit in Angstrom of the output map (e.g. 10.0)
• resolution - low and high resolution (e.g. "3.6 3.4")

pattsize

• map - input patterson map
• binsize - size of radial bins in Angstrom (default 1.0)
• sigma - sigma cutoff to determine size (default 2.0)

mtz2txt

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• resolution - low and high resolution (e.g. "3.6 3.4")

mtz2map

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• fill - fill value for missing reflections (default -1000)
• resolution - low and high resolution (e.g. "3.6 3.4")

map2mtz

• map - input map-file
• resolution - resolution limit (e.g. 2.0)

filter_mtz

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• size - filter size (default 1)
• filter - filter type (gaussian or uniform, default gaussian)
• interpolate - interpolate missing intensities using a normalized convolution (default False)

qdep

• mtz - input mtz-file
• lbl - array of interest (default IDFF)
• sc_size - supercell size (e.g. "5 5 10")
• strong - consider only this number of strongest reflections (default 100)

pdbrad

• pdb - input pdb-file

pdbdist

• pdb - input multistate pdb-file (can be multiple)
• ensemble - ensemble treatment (std, var or mean, default std)
• mode - multiple input treatment (combine, sub, div, add or mul, default combine)

btrace

• input - input pdb or json (can be multiple)
• lines - plot vertical lines at these x-positions (e.g. "25.5 75.5")

References

This software relies on methods described in the following papers:

1. Chapman, Henry N., et al. "Continuous diffraction of molecules and disordered molecular crystals." Journal of applied crystallography 50.4 (2017): 1084-1103.
2. Pearce, Nicholas M., and Piet Gros. "A method for intuitively extracting macromolecular dynamics from structural disorder." Nature communications 12.1 (2021): 5493.
3. Urzhumtsev, Alexandre, et al. "From deep TLS validation to ensembles of atomic models built from elemental motions. Addenda and corrigendum." Acta Crystallographica Section D: Structural Biology 72.9 (2016): 1073-1075.