The structure of a protein provides insight into its physiological interactions with other components of the cellular soup. Methods that predict putative structures from sequences typically yield multiple, closely-ranked possibilities. A critical component in the process is the model quality assessing program (MQAP), which selects the best candidate from this pool of structures. Here, we present a novel MQAP based on the physical properties of sidechain atoms. We propose a method for assessing the quality of protein structures based on the electrostatic potential difference (EPD) of C
β atoms in consecutive residues. We demonstrate that the EPDs of C
β atoms on consecutive residues provide unique signatures of the amino acid types. The EPD of C
β atoms are learnt from a set of 1000 non-homologous protein structures with a resolution cutoff of 1.6 ˚A obtained from the PISCES database. Based on the Boltzmann hypothesis that lower energy conformations are proportionately sampled more, and on Anfinsen's thermodynamic hypothesis that the native structure of a protein is the minimum free energy state, we hypothesize that the deviation of observed EPD values from the mean values obtained in the learning phase is minimized in the native structure. We achieved an average specificity of 0.91, 0.94 and0.93 on hg structal, 4state reduced and ig structal decoy sets, respectively, taken from the Decoys 'R' Us database. The source code and manual is made available at
https://github.com/sanchak/mqap and permanently available on
10.5281/zenodo.7134....

The electrostatic profile of consecutive Cβ atoms applied to protein structure quality assessment [version 3; peer review: 2 approved]

10.12688/f1000research.2-243.v3