Lipoic acid provokes inhibition and aggregation of the maltose binding protein of Escherichia coli.

Lipoic acid provokes aggregation of the monomeric maltose binding protein of Escherichia Coli into dimers and tetramers, and inhibits maltose binding. The sigmoidal shape of the curves showing the dependence of maltose binding versus lipoic acid concentration, and versus maltose concentration (in the presence of lipoic acid) suggests that the inhibition of the maltose binding protein by lipoic acid is a consequence of its aggregation. These results are discussed in relation to recent studies describing dimers of the maltose binding protein purified under certain conditions, and in relation to results suggesting an implication of lipoic acid in the binding protein-dependent transports.