Simultaneous Coordination of Zn(II) and Zr(IV) to d-Amino Acid Oxidase: Highly Efficient Catalytic Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone

d-Amino acid oxidase (DAAO) has been coordinated to Zn(II) and Zr(IV) in phosphate buffered saline (PBS) forming the ∼(ZnHPO4)@DAAO@(ZrHPO4)∼ coordination network. The coordination of the nitrogen-containing groups of DAAO with Zn(II) and Zr(IV) and the hydrogen bonding interactions between DAAO and the metal phosphates contributes to the formation of the coordination network. The coordination network confers the conjugate DAAO@Zn&HPO4&Zr possessing strong Lewis acid sites due to the coordinated Zn (II) and Zr (IV) and strong Lewis base sites attributed to the coordinated N from DAAO and the coordinated O from phosphate. The conjugate DAAO@Zn&HPO4&Zr exhibits a nanoflower-like structure, facilitating the interaction of levulinic acid with the active sites. Ascribing to the above advantages, DAAO@Zn&HPO4&Zr exhibits remarkable catalytic activity for catalytic transfer hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), achieving the LA conversion of 99.8% and the GVL yield of 98.2% at 130 °C within 2 h. In addition, DAAO@Zn&HPO4&Zr exhibited excellent reusability and stability.