Physiological function of periplasmic hexose phosphatase in Salmonella typhimurium.

Hydrolysis of sugar phosphates by crude and purified preparations of periplasmic hexose phosphatase from Salmonella typhimurium followed Michaelis-Menten kinetics. The enzyme bound glucose 1-phosphate with high affinity (Km = 10 microM) but bound glucose 6-phosphate with low affinity (Km = 2,000 microM). The order of substrate affinities was glucose 1-phosphate greater than mannose 1-phosphate = galactose 1-phosphate greater than fructose 1-phosphate greater than glucose 6-phosphate. These results and others suggest that the physiological function of the enzyme is the periplasmic hydrolysis of hexose 1-phosphates.