Relationships between electrophoretic patterns of esterases from Salmonella

Esterases of 85strains of the four biochemically-defined subgenera of Salmonella, when analysed by the acrylamide-agarose zymogram technique using several synthetic substrates, gave four principal bands (E1, E2, E3, E4) and two minor ones. The E1 esterase band hydrolysed alphs-naphthyl acetate, whereas the E2 band hydrolysed beta-naphthyl acetate. These bands were resistant to di-isofluoropropyl phosphate (DFP) and their electrophoretic distribution among the strains occurred within a relatively small MF range, MF being the distance moved by the esterase band as a percentage of the distance moved by the dye front. The E3 band hydrolysed alpha-naphthyl acetate and alpha-naphthyl napbuyyrate and, to a lesser degree, beta-naphthyl esters, whereas the E4 band hydrolysed alpha-naphthyl acetate. These bands were sensitive to DFP and their electrophoretic distribution among the strains occurred in a wide MF range. ALL Salmonella strains were closely related in terms of their esterase profiles. However, the divergences in electrophoretic distribution of bands E3 and E4 were sufficient to recognize the subgenera of most of the Salmonella strains analysed.