BRENDA is a collection of enzyme functional data available to the scientific community. The enzymes are classified according to the Enzyme Commission list of enzymes. Nomenclature, reaction and specificity, isolation/preparation, and structure of more than 4000 different enzymes is covered. BRENDA is maintained and developed at the Institute of Biochemistry and Bioinformatics at the Technical University of Braunschweig, Germany. Data on enzyme function are extracted directly from the primary literature.