PEROXIDE REDUCTASE-ACTIVITY OF NADH DEHYDROGENASE OF AN ALKALIPHILIC BACILLUS IN THE PRESENCE OF A 22-KDA PROTEIN-COMPONENT FROM AMPHIBACILLUS-XYLANUS

The NADH oxidase of Amphibacillus xylanus shows high NADH-peroxide red uctase activity for hydrogen peroxide and alkyl hydroperoxides in the presence of a 22-kDa disulfide-containing protein component (Y. Niimur a, L. B. Poole, and V. Massey, J.Biol.Chem. 270, 25645-25650, 1995). I t was found that the membrane-bound NADH dehydrogenase of an alkaliphi lic Bacillus (YN-1) involved in the respiratory chain also exhibits re ductase activity for hydrogen peroxide and cumene hydroperoxide in the presence of the 22-kDa component from Amphibacillus xylanus. Vmax val ues for these substrates were as high as those of the NADH oxidase of A. xylanus. Although the 38-kDa protein produced by trypsin treatment of NADH dehydrogenase retains NADH dehydrogenase activity, it exhibite d no peroxide reductase activity in the presence of the 22-kDa compone nt from A. xylanus. The NADH dehydrogenase of YN-1 might not only cata lyze electron flow from NADH to the respiratory chain, but also functi on for scavenging peroxide. (C) 1998 Academic Press.