The Catalytic Site Atlas (CSA) is …
The Catalytic Site Atlas (CSA) is a database documenting enzyme active sites and catalytic residues in enzymes of 3D structure. We defined a classification of catalytic residues which includes only those residues thought to be directly involved in some aspect of the reaction catalyzed by an enzyme.

The CSA contains 2 types of entry:
1. Original hand-annotated entries, derived from the primary literature. References for these entries are given.
2. Homologous entries, found by PSI-BLAST alignment (using an e value cut-off of 0.00005) to one of the original entries. The equivalent residues, which align in sequence to the catalytic residues found in the original entry are documented.

Access to the CSA is via PDB code, SWISS-PROT entry or E.C. number. Accessing via PDB code takes you straight to the CSA entry for that PDB, while accessing via SWISS-PROT or E.C. number gives a list of all PDB codes for structures assigned that particular SWISS-PROT identifier or E.C. number. Structures with entries in the CSA are given as hyperlinks.

Each CSA entry lists the catalytic residues found in that entry, using PDB residue numbering. Each site is also marked with an evidence tag, which is either "Literature reference" or "PSI-BLAST hit". If the entry is a PSI-BLAST hit you can follow the link to the original entry.

You may download the CSA.