The phosphoenolpyruvate-dependent glucose phosphotransferase system (PTS) of was studied in toluene-treated cells and cell-free extracts. Toluene-treated cells phosphorylated the non-metabolizable glucose analogue methyl α-glucoside in a PEP-dependent manner, and exhibited apparent values of 93 μ and 12 μ, respectively, for the substrates PEP and methyl α-glucoside. Using cell-free extracts, it was shown that the system consists of both soluble and membrane-bound components. The rate of methyl α-glucoside phosphorylation was dependent on the concentration of both the soluble and membrane fractions, and was independent of the concentration of PEP. Saturation kinetics for PEP were restored in the presence of a partially purified soluble fraction, which appeared to contain a single phosphotransferase component. This was similar to HPr of by the following criteria:(i) it eluted in the same position from a Sephadex G-100 gel filtration column; (ii)it was relatively resistant to exposure to temperatures up to 100 °C; (iii) it was involved in phosphorylation of a number of sugars which enter the cell via different phosphotransferase systems; (iv) the kinetics of methyl α-glucoside phosphorylation required the soluble protein in to be a substrate rather than an enzyme.


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