(263f) Alkyl Hydroperoxide Reductase & Water-Forming Nadh Oxidase: Comparison and Application for Selective Oxidations

NADH oxidases are useful biocatalysts for regenerating nicotinamide cofactors of many biological redox reactions. In this presentation, we compare the alkyl hydroperoxide reductase (AhpR) and the H₂O-forming enzyme (nox-2) from Lactococcus lactis(L. lactis), as well as the H₂O-former from Lactobacillus sanfranciscensis (L. sanfranciscensis). AhpR is composed of H₂O₂-forming NADH oxidase (nox-1) and peroxidase and the net reaction of AhpR is the same as nox-2. Both nox-1 and nox-2 are flavoproteins and turnover-limited. In the absence of exogenously added thiols, both nox-1 and nox-1/peroxidase are considerably more stable against overoxidation than nox-2. Nox-2 from L. sanfranciscensis was crystallized and was found to have ADP ligand, but according to the HPLC results, no ADP ligand was found in the L. lactis nox-2 protein. We will use enzyme membrane reactor for the application of oxidative biocatalysis reactions with various alcohol dehydrogenases or ketoreductases and these flavoproteins.