(316f) Construction of Artificial Metalloenzyme Catalyst and the Study of Size Effect

The incompatibility between enzyme
and metal catalyzed reactions is a critical issue in integrating chemoenzymatic cascade processes. In this study, we report the
synthesis of temperature-responsive lipase-palladium nanohybrids
(Pluronic-CALB-Pd) with the
size of Pd NPs ranging from 0.8 nm to 2.5 nm. As the Pd NPs downsizing to sub-nanoclusters,
the catalytic performance of Pluronic-CALB-Pd in racemization of (S)-1-phenylethylamine was dramatically
improved and even exhibited efficient catalytic activity at 55 ^oCwhich perfectly matched the
optimal temperature of CALB. The yield of dynamic kinetic resolution (DKR) of racemic
1-phenylethylamine catalyzed by Pluronic-CALB-Pd_1.61 was up to 96 %
and 99 e.e. at 55 ^oC
for 12 h. The catalytic performance was greatly enhanced compared to the
combination of commercially available Novozym 435 and
Pd/C. In addition, the Pluronic-CALB-Pd nanohybrids can be homogeneously
dispersed in organic solvents at relatively high temperature (>50 ^oC) and be precipitated at ambient temperature
for an easy reuse after reaction.

Figure 1. Catalytic performance of Pluronic-CALB- Pd nanohybrids
in the racemization of (S)-1-phenylethylamine