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Other tools to check quality of the predicted structures

Users who wish to further evaluate the quality of predicted protein structures from AlphaFold2 can use a variety of open-source tools.

Open-source tools for evaluating predicted structures

One option is a general structural biology validation tool like MolProbity. These are used for diagnosing “correctness” in 3D models of proteins, nucleic acids or complexes. AlphaFold2 models generally have excellent geometrical quality in high-confidence regions. Nevertheless, if MolProbity flags part of the structure, you should examine it carefully.

For protein-protein complexes, tools like PISA can be used to further assess the quality of the predicted interface. The software allows you to check details like the total buried surface area and the number of cross-interface hydrogen bonds, which in turn give an indication of whether the predicted interface corresponds to reality or is artefactual. Note that PISA validation criteria may have some exceptions, e.g. strongly bound antibody-antigen complexes could be reported as weakly bound by PISA.

The PAE viewer is a web server designed to facilitate the interpretation of PAE scores for multimeric predictions. The visualisation highlights the violations and/or satisfactions of crosslinker length restraints.