P. Hoffee, E. Englesberg, F. Lamy
Mar 30, 1964
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0
Influential Citations
79
Citations
Quality indicators
Journal
Biochimica et biophysica acta
Abstract
Abstract 1. 1. The accumulation of [14C7]α-methyl- D -glucopyranoside is a measure of a glucose permease system in Salmonella typhimurium and Escherichia coli. 2. 2. The steady-state level of α-methyl- D -glucopyranoside (α-MG) accumulation reached in these cells is depressed several fold by the addition of an exogenous energy source upon which the cells have been grown. This depressing effect can be nullified by the addition of metabolic poisons such as azide or dinitrophenol, or by anaerobic conditions. Experiments indicate that this effect cannot be explained by non-specificity of the permease, competition for a common transporter or physical replacement of α-MG by the added carbon source, but indicate that the glucose permease system possesses an exit reaction which is dependent on metabolic energy. 3. 3. Kinetic data, obtained by measuring the steady-state concentration level, the rate of uptake and the rate of loss of α-MG in the presence and absence of an exogenous energy source, demonstrate the presence in this system of another exit reaction besides the energy-requiring exit reaction, and a separate entrance reaction. The entrance reaction is also energy dependent, but is less sensitive to limitations of the available energy. 4. 4. A model is proposed which is consistent with these results.