Alternate Representation of Distance Matrices for Characterization of Protein Structure

  • Authors:
  • Keith Marsolo;Srinivasan Parthasarathy

  • Affiliations:
  • Ohio State University;Ohio State University

  • Venue:
  • ICDM '05 Proceedings of the Fifth IEEE International Conference on Data Mining
  • Year:
  • 2005

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Abstract

The most suitable method for the automated classification of protein structures remains an open problem in computational biology. In order to classify a protein structure with any accuracy, an effective representation must be chosen. Here we present two methods of representing protein structure. One involves representing the distances between the Cá atoms of a protein as a two-dimensional matrix and creating a model of the resulting surface with Zernike polynomials. The second uses a wavelet-based approach. We convert the distances between a protein's Cα atoms into a one-dimensional signal which is then decomposed using a discrete wavelet transformation. Using the Zernike co-efficients and the approximation coefficients of the wavelet decomposition as feature vectors, we test the effectiveness of our representation with two different classifiers on a dataset of more than 600 proteins taken from the 27 most-populated SCOP folds. We find that the wavelet decomposition greatly outperforms the Zernike model.With the wavelet representation, we achieve an accuracy of approximately 56%, roughly 12% higher than results reported on a similar, but less-challenging dataset. In addition, we can couple our structure-based feature vectors with several sequence-based properties to increase accuracy another 5-7%. Finally, we use a multi-stage classification strategy on the combined features to increase performance to 78%, an improvement in accuracy of more than 15-20% and 34% over the highest reported sequence-based and structure-based classification results, respectively.