Rongrong Jiang, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, GA 30332-0363, William B. Wellborn, Georgia Tech, 315 Ferst Drive, Atlanta, GA 30332-0363, and Andreas S. Bommarius, Georgia Institute of Technology, School of Chemical Engineering, 315 Ferst Drive N.W., Parker H. Petit Biotechnology Institute, Room 3310, Atlanta, GA 30332-0363.
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.