l-Arginine inhibits the activity of α-amylase: Rapid kinetics, interaction and functional implications

In this work, the rapid unfolding kinetics of pancreas α-amylase (PPA) induced by l -arginine and the interaction mechanism were investigated. The unfolding followed a first-level reaction kinetics equation, without intermediates. l -arginine interacted with PPA though diffusion-controlled process rather than complexion. The interaction between l -arginine and PPA resulted in a pronounced decrease in β-sheet and a significant increase in random coil, and thereby the enzyme activity decreased. However, the unfolding of PPA could be compensated and the second structure change could be recovered to some extent by the macromolecular crowded medium of Pluronics. Further insight into the mechanism disclosed that the broken H-bond network of water may contribute to PPA unfolding. This work provides a new perspective on the interaction of l -arginine with digestive enzyme. The unfolding mechanism of enzymes by may help to understand the effects of other structurally similar drugs, which is of concern in food-drug interactions.