Crystal density and Matthews coefficient in PDB
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If we divide the sum of the masses of all the atoms in the unit cell
of the crystal by the unit cell volume, we get a crystal density. When
evaluating the density of protein crystals, it is necessary to
remember that the protein molecules are large compared to the solvent
molecules. After the protein molecules are packed in the crystals,
they remain between them sufficiently large gaps that are filled by
the solvent (water, salts ions, small molecules of organic
substances). What would be you guess regarding what size these spaces
are encountered in typical protein crystals?

The volume of the solvent channels could be determined if we knew it
ourselves volume of protein molecules. The surface of the protein
molecule and the volume covered by it it is not quite easy to
calculate, but it is possible to estimate it, using the fact that the
density of practically all globular proteins is almost the same. Find
the value of this density in the literature.

Questions:

- what is the solvent volume of various protein crystal structures
  percent?

- what are the crystal density values of various proteins? What their
  specific volume (V/m [Å**3/Da], called Matthews factor)?  How are
  these sizes distributed? Do they depend on the protein molecule?
  size? From the elementary cage volume?

Program:

This research requires a program that reads PDB archive files and
calculates and outputs the percentage of crystal solvent based on
their data, density and specific volume.