Zinc hydroxide salts as new supports for the immobilization of Pseudomonas cepacia lipase

Layered double hydroxides (LDHs) are brucite-like nanomaterials that have been used to immobilize several enzymes. However, layered hydroxide salts (LHSs), another group of brucite-like nanomaterials, have not yet been used for enzyme immobilization. In this work, we prepared two types of layered hydroxide salts, zinc hydroxide nitrate (ZHN: Zn-5(OH)(8)(NO3)(2)(.)2H(2)O) and zinc hydroxide chloride (ZHC: Zn-5(OH)(8)(Cl2H2O)-H-.) and used them to immobilize Pseudomonas cepacia lipase (LipPS). The best protein loading for both ZHN and ZHC was 162.5 mg g(-1) of LHS, which gave high values of triolein-hydrolyzing activity in organic medium (103 U g(-1) for LipPS-ZHN and 105 U g(-1) for LipPS-ZHC), immobilization efficiencies above 90% and activity retentions above 170%. In the kinetic resolution of (R,S)-1-phenylethanol, LipPS-ZHN gave better results, with 50% conversion being obtained in 2 h and an ee(s) of 99%. With LipPS-ZHC, the conversion at 2 h was 40% and the ee(s), was lower, only 73%. For both immobilized materials, the ee(p) was higher than 99% and E was higher than 200. The immobilized materials were stable after 5 cycles of reuse in successive 2-h kinetic resolutions. These results demonstrate that the layered hydroxide salts ZHN and ZHC have good potential as supports for the immobilization of lipases.