초록
<P><B>Abstract</B></P> <P> <I>R</I>-ɷ-transaminases transfer an amino group from an amino donor (e.g. (<I>R</I>)-1-phenylethylamine) onto an amino acceptor (e.g. pyruvate), resulting a co-product (e.g. <SMALL>D</SMALL>-alanine). This work intends to immobilize <I>R</I>-ɷ-Transaminase on MnO<SUB>2</SUB> nanorods to achieve multienzyme catalysis. <I>R</I>-ɷ-Transaminase (RTA) and <SMALL>D</SMALL>-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<SUB>2</SUB> nanorods. When the two immobilized enzymes were used together in one pot, the transformation of (<I>R</I>)-1-phenylethylamine was catalyzed by the immobilized ELP-RTA, and the co-product <SMALL>D</SMALL>-alanine was converted back to pyruvate under the catalysis of the immobilized ELP-DAAO, achieving the recycling of pyruvate <I>in situ</I>. Thus pyruvate was maintained at a low concentration in order to reduce its negative effect. On the other hand, the generated H<SUB>2</SUB>O<SUB>2</SUB> of ELP-DAAO was decomposed by the MnO<SUB>2</SUB> 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 <SMALL>D</SMALL>-alanine back to pyruvate accelerated the forming of the pyruvate <B>→</B> <SMALL>D</SMALL>-alanine→pyruvate cycle between the two immobilized enzymes. The coordination of the pyruvate <B>→</B> <SMALL>D</SMALL>-alanine <B>→</B> pyruvate and hydrogen peroxide→oxygen→hydrogen peroxide cycles accelerated the transformation of (<I>R</I>)-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.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <SMALL>D</SMALL>-amino acid oxidase (ELP-DAAO) and <I>R</I>-ɷ-transaminases (ELP-RTA) were separately immobilized on the polydopamine-coated MnO2 nanorods. </LI> <LI> The immobilized ELP-RTA catalyzed the conversion of (<I>R</I>)-1-phenylethylamine with pyruvate as an amine acceptor. </LI> <LI> The immobilized ELP-DAAO catalyzed the conversion of <SMALL>D</SMALL>-alanine to pyruvate, the generated hydrogen peroxide was decomposed by the MnO<SUB>2</SUB> nanorods. </LI> <LI> The immobilized enzymes achieved a conversion of 98±1.8% in comparison to 69.6±1.2% by free enzymes. </LI> </UL> </P>