Bioinformatics Advance Access published online on March 17, 2009
Bioinformatics, doi:10.1093/bioinformatics/btp150
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Artefacts and biases affecting the evaluation of scoring functions on decoy sets for protein structure prediction
1 Faculty of Life Sciences, University of Manchester, UK
2 School of Computer Science, University of Manchester, UK
*To whom correspondence should be addressed. Simon C. Lovell, E-mail: simon.lovell{at}manchester.ac.uk
| Abstract |
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Motivation: Decoy data sets, consisting of a solved protein structure and numerous alternative native-like structures, are in common use for the evaluation of scoring functions in protein structure prediction. Several pitfalls with the use of these data sets have been identified in the literature, as well as useful guidelines for generating more effective decoy data sets. We contribute to this ongoing discussion an empirical assessment of several decoy data sets commonly used in experimental studies.
Results: : Results: We find that artefacts and sampling issues in the large majority of these data make it trivial to discriminate the native structure. This underlines that evaluation based on the rank / z-score of the native is a weak test of scoring function performance. Moreover, sampling biases present in the way decoy sets are generated or used can strongly affect other types of evaluation measures such as the correlation between score and RMSD to the native. We demonstrate how, depending on type of bias and evaluation context, sampling biases may lead to both over- or under-estimation of the quality of scoring terms, functions or methods.
Availability: Links to the software and data used in this study are available at http://dbkgroup.org/handl/decoy_sets.
Contact: simon.lovell{at}manchester.ac.uk
Associate Editor: Prof. Anna Tramontano
Received on October 29, 2008; revised on March 6, 2009; accepted on March 14, 2009