Nucleic Acids Research, 2009, Vol. 37, Database issue D591 Table 3. Data ﬁelds supported by the BRENDA SOAP interface Activating_Compound Application CAS_Registry_Number Cloned Cofactor Crystallization Disease EC_Number Engineering Enzyme_Names General_Stability Inhibitors KEGG_Pathway KI_Value KM_Value Ligands Localization Metals_Ions Molecular_Weight Natural_Product Natural_Substrate Natural_Substrates_Products Organic_Solvent_Stability Organism Organism_synonyms Oxidation_Stability PDB pH_Optimum pH_Range pH_Stability pI_Value Posttranslational_Modiﬁcation Product Puriﬁcation Reaction Reference Reaction_Type Recommended_Name Renatured Sequence Source_Tissue Speciﬁc_Activity Storage_Stability Substrate Substrates_Products Subunits Synonyms Systematic_Name Temperature_Optimum Temperature_Range Temperature_Stability Turnover_Number above yields a precision of 75% and a recall of 25% for enzyme-organism combinations for the two highest reli- ability ranks (AMENDA reliability +++ and ++++). When the lower AMENDA reliability rank ++ is also included, the precision is reduced to 56%, whereas the recall increases to 55%. As the BRENDA enzyme name dictionary contains on average approximately 10 diﬀerent names per enzyme class (with several hundred names in use for some enzyme classes) the information contents in FRENDA is much more complete than a simple PubMed search using one or two names for an enzyme known to the scientist. INTEROPERABILITY BY SOAP-BASED WEB SERVICES A web service is a software system which allows interoper- able machine-to-machine communication via a computer network such as the Internet. Thus, it facilitates access to databases hosted on remote servers that oﬀer the web service and even allows executing remote query operations on these machines. The advantage for the web service using computer is that no download and parsing of the complete database is required and changes of the data- base structure are negligible if the API (Application Programming Interface) remains the same. Since the release of June 2006 (3) BRENDA oﬀers a SOAP-based web service API (http://www.brenda- enzymes.org/soap). It covers more than 50 diﬀerent data ﬁelds (Table 3) and provides access to them via almost 150 diﬀerent remote methods. For all data ﬁelds in the record sets the correspond- ing literature references can be obtained. The methods for querying the individual data ﬁelds accept either the organism, the EC number or—where meaningful—the ligand identiﬁer or combinations of all three as input parameters. A critical point of a web service is the complexity of its API and the interoperability with many diﬀerent program- ming languages. Following the user feedback, the SOAP interface of BRENDA has been simpliﬁed with respect to the used data types. The data types of the return values of the new SOAP API (http://www.brenda-enzymes.org/ soap2) which will be made available from January 2009 use exclusively strings and which are supported by almost every programming language. For compatibility reasons the old SOAP interface (http://www.brenda-enzymes.org/soap) will remain online for some time but is no longer actively supported. Examples of client code snippets and a full documentation of the web service’s capabilities can be found on the above speciﬁed URLs. FUNDING European Union (FELICS, Free European Life-Science Information and Computational Services: 021902 (RII3)). Funding for open access charge: FELICS, Free European Life-Science Information and Computational Services. Conﬂict of interest statement: None declared. REFERENCES 1. Schomburg,D. and Schomburg,I. (2001–2007) Springer Handbook of Enzymes, 2 edn., Springer, Heidelberg, Germany. 2. Schomburg,I., Chang,A., Ebeling,C., Gremse,M., Heldt,C., Huhn,G. and Schomburg,D. (2004) BRENDA, the enzyme data- base: updates and major new developments. Nucleic Acids Res., 32, D431–D433. 3. Barthelmes,J., Ebeling,C., Chang,A., Schomburg,I. and Schomburg,D. (2007) BRENDA, AMENDA and FRENDA: the enzyme information system in 2007. Nucleic Acids Res., 35, D511–D514. 4. Sonnhammer,E.l.L., von Heijne,G. and Krogh,A. (1998) A hidden Markov model for predicting transmembrane helices in protein sequences. In Glasgow,J., Littlejohn,T., Major,F., Lathrop,R., Sankoﬀ,D. and Sensen,C. (eds), Proceedings of the Sixth International Conference on Intelligent Systems for Molecular Biology, AAAI Press, Menlo Park, CA, pp. 175–182. 5. Webb,E.C. and NC-IUBMB. (1992) Enzyme Nomenclature: Recom- mendations of the Nomenclature Committee of the International Union