The EC (Enzyme Commission) browser presents proteins in the PDB based on the type of enzyme function it performs. Enzymes are classified based on the recommendations of the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB). For each enzyme in the archive an EC number has been provided (see EC). These assignments are based on UniProtKB/GenBank/KEGG/author specified mapping of the enzyme to EC numbers.
Here you can browse the EC tree by an enzyme or enzyme class name, view the number of associated PDB proteins, and search for the specific associated structures either by enzyme name or by partial/full EC number.