A kinetic study of pig liver glucose dehydrogenase.

Utilizing a temperature-sensitive mutant of Escherichia coli K-12 defective in the coupling of metabolic energy to active transport, we have demonstrated that the uptake systems for arabinose, galactose, valine, histidine, and glutamine, which are sensitive to the osmotic shock treatment of L. A. Heppel (1965) (J. Biol. Chem.240, 3685), are all totally defective at the nonpermissive temperature (42 °C) whereas the intracellular ATP levels increase twofold. Phosphate bond energy alone is therefore not sufficient to energize the transport of these substrates. We have confirmed the findings of E. A., Berger and L. A. Heppel (1974) (J. Biol. Chem. 249, 7747) regarding a severe arsenate I inhibition of the uptake of substrates belonging to osmotic shock-sensitive transport systems and therefore conclude that both ATP and a functional ecf gene product are required for the coupling of energy to the transport of these solutes.