Abstract
Tributyltin chloride inhibits growth and uptake of glutamine and proline into intact cells of Escherichia coli. It causes efflux of the accumulated amino acids. A pH gradient generated in intact cells and everted membrane vesicles is dissipated by this compound. These effects do not require lipoic acid but are dependent on the presence of chloride, bromide, or iodide ions. We conclude that tributyltin chloride can catalyse a transmembrane OH–anion exchange reaction and that this is its mode of inhibition of the uptake of these amino acids. The response of proline and glutamine uptake to the inhibitor is similar and is consistent with the transport of both amino acids requiring an electrochemical gradient of protons.