Manipulation of protein fingerprints during on-column fluorescent labeling: Protein fingerprinting of six Staphylococcus species by capillary electrophoresis

Bacterial proteomes were analyzed by use of electrophoretically mediated mi croanalysis (EMMA) and field-enhanced stacking. A water-soluble protein fra ction was injected onto a capillary. Next, a fluorogenic reagent was inject ed and allowed to react with the protein mixture, producing fluorescent pro ducts that were separated by submicellar capillary electrophoresis and dete cted by laser-induced fluorescence. By use of a low-ionic strength sample b uffer and a brief electrophoretic step, slow moving anionic proteins were s tacked at the reagent-sample interface and were preferentially labeled. By reversing the order of sample injection and labeling reagent, fast moving c ationic proteins were preferentially labeled. By adjustment of the sample b uffer pH, proteins with different isoelectric points were selectively label ed. Electrophoresis fingerprints were generated for the water-soluble prote in fraction from six Staphylococcus species. The protein patterns produced were species-specific and were used to construct a phylogenetic tree.