Binding of various ligands to purified OpuAC using intrinsic protein fluorescence.

Dissociation constants (KD) and inhibition constants (KI) of various ligands bound to OpuAC measured either directly (KD) or via inhibition of glycine betaine binding (KI), using intrinsic protein fluorescence. The dissociation constants were averaged from at least duplicate measurements, fitted independently to obtain the dissociation constants (for KD); for the KI-values, inhibition was measured over a range of inhibitor concentrations and the KI values were averaged and the errors indicate the range.