Aerobic and anaerobic functioning of superoxide-producing cytochrome b-559 reconstituted with phospholipids.

Cytochrome b-559 reconstituted with phospholipids and FAD represents the simplest model of the respiratory burst NADPH oxidase and reproduces the main catalytic features of this system (Koshkin, V. and Pick, E. (1993) FEBS Lett. 327, 57-62; (1994) FEBS Lett. 338, 285-289). In the present report it is shown that activation by oxygen, characteristic of the NADPH oxidase complex, is an intrinsic property of flavocytochrome b-559, in principle independent of its complexation with the other components of NADPH oxidase. Facilitation of electron transfer from NADPH to FAD is found to be the reason for this phenomenon. Kinetic studies of anaerobic operation of flavocytochrome b-559 revealed the functional heterogeneity of two hemes, manifested as a dramatic difference in their reducibility under these conditions.