The RESID Database is a comprehensive collection of annotations and structures for protein pre-, co- and post- translational modifications including amino- terminal, carboxyl- terminal and peptide chain cross- link modi cations. The RESID Database includes: systematic and alternate names, atomic formulas and masses, enzyme activities generating the modi cations, keywords, literature citations, Gene Ontology cross- references, Protein Information Resource ( PIR) and SWISS- PROT protein sequence database feature table annotations, structure diagrams and molecular models. This database is freely accessible on the Internet through the European Bioinformatics Institute at http: / / srs. ebi. ac. uk/ srs6bin/ cgi- bin/ wgetz? - page+ LibInfo+ - lib+ RESID, through the National Cancer Institute Frederick Advanced Biomedical Computing Center at http: / / www. ncifcrf. gov/ RESID, or through the Protein Information Resource at http: / / pir. georgetown. edu/ pirwww/ dbinfo/ resid. html.