Abstract
The oxidase responsible for the“respiratory burst” of phagocytosing polymorphonuclear leukocytes (PMN) was reviewed with recent works on the cellular and subcellular fractions of PMN. (1) In view of the kinetic studies on the oxidase, we concluded that the actual substrate is NADPH but not NADH. (2) NADPH oxidase is located in the plasma membranes. The inhibitory effect of Cibacron-Blue F3GA on the oxidase suggests that the NADPH binding site of the oxidase is located on the inner surface of the plasma membrane. The O-2-releasing site seems to be located on the outer surface of the plama membrane. (3) The nitrogen-cavitation method, which pinches off plasma membrane fragments from cells, separated NADPH-oxidase rich and poor vesicles from plasma membranes. The results suggest that activation of PMN either by soluble stimulators or bacteria, leads to a heterogeneous distribution of NADPH oxidase on the plasma membrane. (4) Inhibitors on NADPH oxidase in membrane vesicles are summarized. Some inhibitors suggest that hydrophobic portions of plasma membranes play some role in the O-2-generating activity. (5) A fraction of plasma membranes, in which a high specific activity of NADPH oxidase is located, contained not only a cytochrome b but also a FAD-binding protein.
