Using physical features of protein core packing to distinguish real proteins from decoys

Alex T. Grigas, Zhe Mei, John D. Treado, Zachary A. Levine, Lynne Regan, Corey S. O'Hern

Research output: Contribution to journalArticlepeer-review


The ability to consistently distinguish real protein structures from computationally generated model decoys is not yet a solved problem. One route to distinguish real protein structures from decoys is to delineate the important physical features that specify a real protein. For example, it has long been appreciated that the hydrophobic cores of proteins contribute significantly to their stability. We used two sources to obtain datasets of decoys to compare with real protein structures: submissions to the biennial CASP competition, in which researchers attempt to predict the structure of a protein only knowing its amino acid sequence, and also decoys generated by 3DRobot, which have user-specified global root-mean-squared deviations from experimentally determined structures. Our analysis revealed that both sets of decoys possess cores that do not recapitulate the key features that define real protein cores. In particular, the model structures appear more densely packed(because of energetically unfavorable atomic overlaps), contain too few residues in the core, and have improper distributions of hydrophobic residues throughout the structure. Based on these observations, we developed a feed-forward neural network, which incorporates key physical features of protein cores, to predict how well a computational model recapitulates the real protein structure without knowledge of the structure of the target sequence. By identifying the important features of protein structure, our method is able to rank decoy structures with similar accuracy to that obtained by state-of-the-art methods that incorporate many additional features. The small numbe rof physical features makes our model interpretable, emphasizing the importance of protein packing and hydrophobicity in protein structure prediction.
Original languageEnglish
Pages (from-to)1931-1944
Number of pages14
JournalProtein Science
Issue number9
Early online date25 Jul 2020
Publication statusPublished - 28 Aug 2020


  • protein decoys
  • hydrophobic core
  • protein structure prediction
  • protein design


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