In the KEGG implementation of Enzyme Nomenclature, the EC numbers are associated, whenever available, with sequence data of enzymes used in the original experiments according to the reference information (see KEGG ENZYME).
The following tables contain manually identified sequence data and computationally linked 3D structure data.
GenBank - author submitted nucleotide sequence data
NCBI Protein - enzyme sequence data in this submission
KEGG GENES - identified enzyme sequence data in KEGG (also used for defining KOs)
PDB - enzyme 3D structure data (computationally linked by matching PubMed IDs)