The kinetics of the β-galactoside-proton symport of Escherichia coli

Abstract

.beta.-Galactoside transport by E. coli occurs with the concomitant uptake of a proton. The kinetics of .beta.-galactoside uptake at various values of external pH are interpreted in terms of a model in which both the galactoside and the proton are substrates of the transport reaction. The values of some of the kinetic constants for this 2-substrate reaction were determined. The observed effects of the proton motive force on the apparent Km for galactoside can be explained in terms of the proton being a substrate of the transport reaction.