Stabilization of Alkaline Phosphatase with Au@Ag2O Nanoparticles

Here, we report that a conductive Au@Ag2O nanoparticle structure significantly enhances the stability of alkaline phosphatase (AlkP) in the presence of the inhibitors urea and L-phenylalanine (Phe). The enzyme/nanoparticle construct is prepared by associating the enzyme with citrate-capped Au particles, and then adding Ag+. UV-vis and XPS spectroscopy and transmission electron microscopy confirm the core@shell structure. AlkP activity was quantified in the presence and absence of the two inhibitors using a time-resolved colorimetric assay. The results indicate that 21% of the initial active AlkP is incorporated into the nanoparticle structure. More importantly, however, the Au@Ag2O core@shell host reduces the inhibitory effect of urea and Phe by factors ranging from 3 to 12, depending on the inhibitor and its concentration, compared to the wildtype enzyme.