1) Checks the stereochemical quality of a protein structure by analyzing residue-by-residue geometry and overall structure geometry. [Reference]
2) Does extensive checking of many sterochemical parameters of the residues in the model. [Reference]
3) Analyzes the statistics of non-bonded interactions between different atom types and plots the value of the error function versus position of a 9-residue sliding window, calculated by a comparison with statistics from highly refined structures. [Reference]
4) Determines the compatibility of an atomic model (3D) with its own amino acid sequence (1D) by assigned a structural class based on its location and environment (alpha, beta, loop, polar, nonpolar etc) and comparing the results to good structures. [Reference]
5) Calculates the volumes of atoms in macromolecules using an algorithm which treats the atoms like hard spheres and calculates a statistical Z-score deviation for the model from highly resolved (2.0 Å or better) and refined (R-factor of 0.2 or better) PDB-deposited structures. [Reference]
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