Catalytic Residue Prediction (CPR) extracts features from sequence, sequence alignments, three-dimensional structure, and structural environment conservation and uses support vector machines (SVM) to annotate homologous and nonhomologous catalytic residue positions in enzymes. This tool requires a Protein Data Bank (PDB) file and an email address. A score to classify an amino acid residue to have catalytic activity is then provided. For more information see Youn E, Peters B, Radivojac P, Mooney SD. Protein Sci. 2007 16(2):216-26.