Immobilization of R-ω-transaminase on MnO2 nanorods for catalyzing the conversion of (R)-1-phenylethylamine.

R -ɷ-transaminases transfer an amino group from an amino donor (e.g. ( R )-1-phenylethylamine) onto an amino acceptor (e.g. pyruvate), resulting a co-product (e.g. d -alanine). This work intends to immobilize R -ɷ-Transaminase on MnO 2 nanorods to achieve multienzyme catalysis. R -ɷ-Transaminase (RTA) and d -amino acid oxidase (DAAO) have been fused to an elastin-like polypeptide (ELP) separately through genetic engineering of the enzymes. ELP-RTA and ELP-DAAO have been separately immobilized on polydopamine-coated MnO 2 nanorods. When the two immobilized enzymes were used together in one pot, the transformation of ( R )-1-phenylethylamine was catalyzed by the immobilized ELP-RTA, and the co-product d -alanine was converted back to pyruvate under the catalysis of the immobilized ELP-DAAO, achieving the recycling of pyruvate in situ . Thus pyruvate was maintained at a low concentration in order to reduce its negative effect. On the other hand, the generated H 2 O 2 of ELP-DAAO was decomposed by the MnO 2 nanorods, and the evolved oxygen oxidized the reduced cofactors of ELP-DAAO. Forming the circles of hydrogen peroxide → oxygen → hydrogen peroxide accelerated the deamination reaction. The highly efficient conversion of the co-product d -alanine back to pyruvate accelerated the forming of the pyruvate → d -alanine → pyruvate cycle between the two immobilized enzymes. The coordination of the pyruvate → d -alanine → pyruvate and hydrogen peroxide → oxygen → hydrogen peroxide cycles accelerated the transformation of ( R )-1-phenylethylamine. As a result, As a result, the immobilized enzymes achieved a conversion of 98 ± 1.8% in comparison to 69.6 ± 1.2% by free enzymes. [ABSTRACT FROM AUTHOR]