Displacement binding allosteric interaction

When substances that themselves bind to specific sites on SA are added to the mobile phase, competitive displacements, that is, a lowering of k and a, are not the only possibilities. There is also the potential for an allosteric interaction to occur in which the affinity of the protein for the solute is increased by the addition of the modifier. For example, the addition of 10 jiM (S)-WAR to the mobile phase increased the k of the S-enantiomers of lorazepam and lorazepam hemisuccinate by 4 and 72%, respectively (113). The k s of the R-enantiomers were not affected and, therefore, the observed a s increased by 5 and 76%, respectively. These results not only increased the chromatographic separation of the respective enantiomers, but also indicated that there was an allosteric interaction between WAR and S)-Iorazepam and (S)-lorazepam hemisuccinate. 

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