Arrangement of the respiratory burst oxidase in the plasma membrane of the neutrophil

Abstract

Evidence was obtained regarding the way the O2--forming NADPH oxidase of human neutrophils is arranged within the plasma membrane. O2--production by particles from zymosan-activated human neutrophils rose two- to threefold when the particles were assayed in the presence of appropriate concentrations with trypsin or with p-chloromercuribenzene sulfonate, a nonpenetrating sulfhydryl reagent, but the activity detectable in the absence of detergent was abolished by these treatments. O2--production by phagocytic vesicles was not augmented by detergent, and was almost entirely eliminated by tryptic digestion of the vesicles regardless of whether or not detergent was present during the assay. These results suggest that the O2--forming oxidase is embedded in the plasma membrane with a portion extending into the cytoplasm and the rest buried in the lipid bilayer. It is proposed that the pyridine nucleotide-binding site is located on the cytoplasmic extension and the oxygen binding site is on the intramembranous portion of the enzyme.