BRENDA is a comprehensive database of enzymes maintained by the Institute of Biochemistry at the University of Cologne. Scientists collect and evaluate enzyme function data from primary literature sources. The site has recently been updated with new enzymes and an entirely new search engine. Various searches can be performed, including enzyme name, organism, or EC number. Links to literature citations, two dimensional images, and other databases are included for many of the enzymes. Academic and nonprofit use is free; commercial users must acquire a license.