Highly active enzyme–metal nanohybrids synthesized in protein–polymer conjugates

Building a bridge between enzymatic and heterogeneous catalysis provides new cascade industrial processes for manufacturing. However, the reaction conditions of enzymatic and heterogeneous catalysis mutually cause deactivation of catalysts. Here, we overcame this challenge by developing a special protocol for the synthesis of hybrid catalysts. We utilized protein–polymer nanoconjugates as confined nanoreactors for the in situ synthesis of lipase–palladium (Pd) nanohybrids. The 0.8 nm Pd nanoparticles exhibited increased activity in racemization of (S)-1-phenylethylamine. At 55 °C, which matches the optimum temperature of lipase, the activity is more than 50 times that of commercial Pd/C. It was found that the Pd–O coordination in Pd subnanoclusters contributed to the high activity. In the dynamic kinetic resolutions of pharmaceutical intermediates (±)-1-phenylethylamine, (±)-1-aminoindan and (±)-1,2,3,4-tetrahydro-1-naphthylamine, the lipase–Pd nanohybrids displayed 7.6, 3.1 and 5.0 times higher efficiencies than the combination of commercial immobilized lipase Novozym 435 and Pd/C. The lipase–Pd nanohybrids can be reused without agglomeration and activity loss. Combining enzymatic and heterogeneous catalysts is challenging due to different reaction requirements. Here, a method is presented constructing single protein–polymer nanoconjugates as nanoreactors for the in situ synthesis of enzyme–metal nanohybrids with high activity at ambient conditions.