FROM PROTEINS TO PROTEOMES - LARGE-SCALE PROTEIN IDENTIFICATION BY 2-DIMENSIONAL ELECTROPHORESIS AND AMINO-ACID-ANALYSIS

Separation and identification of proteins by two-dimensional (2-D) ele ctrophoresis can be used for protein-based gene expression analysis, I n this report single protein spots, from polpvinylidene difluoride blo ts of micropreparative E. coli 2-D gels, were rapidly and economically identified by matching their amino acid composition, estimated pi and molecular weight against all E. coli entries in the SWISS-PROT databa se. Thirty proteins from an E. coli 2-D map were analyzed and identiti es assigned. Three of the proteins were unknown. By protein sequencing analysis, 20 of the 27 proteins were correctly identified, Importantl y, correct identifications showed unambiguous ''correct'' score patter ns. While incorrect protein identifications also showed distinctive sc ore patterns, indicating that protein must be identified by other mean s. These techniques allow large-scale screening of the protein complem ent of simple organisms, or tissues in normal and disease states, The computer program described here is accessible via the World Wide Web a t URL address (http://expasy.hcuge.ch/).