The advantage of biosensor analysis over enzyme inhibition studies for slow dissociating inhibitors – characterization of hydroxamate-based matrix metalloproteinase-12 inhibitors
Thomas Gossas, Helena Nordström, Ming-Hua Xu, Zhi-Hua Sun, Guo-Qiang Lin, Hans Wallberg
and U. Helena Danielson. Med. Chem. Commun., 2013, 4(2),432-442
The kinetic characteristics of hydroxamate-based inhibitors of matrix metalloproteinase (MMP)-12 were explored using an SPR biosensor-based assay and enzyme inhibition analysis. These high-affinity inhibitors were shown to dissociate very slowly from the enzyme–inhibitor complex while a carboxylate analogue had a much faster dissociation rate, verifying the importance of the hydroxamate group for the slow dissociation. Progress curve enzyme inhibition analysis confirmed that the hydroxamate compounds but not the carboxylate compound acted as time-dependent inhibitors. The slow dissociation excluded steady-state estimation of IC50-values and Ki values but also made Ki values from progress curve analysis unreliable. Although a full characterization of the inhibitors using biosensor analysis was limited by slow dissociation, it provided kinetic and mechanistic information of relevance for MMP drug discovery and avoided some pitfalls of conventional enzyme inhibition assays.