ISOLATION OF A COMPLEX OF RESPIRATORY BURST OXIDASE COMPONENTS FROM RESTING NEUTROPHIL CYTOSOL

The respiratory burst oxidase of neutrophils is a multicomponent enzyme, dormant in resting cells, that catalyzes the reduction of oxygen to O2(-) at the expense of NADPH. In the resting neutrophil, some of the components of the oxidase, including proteins p47(phox) and p67(phox) are in the cytosol, while the rest are in a fraction that usually copurifies with plasma membrane. Recent evidence has suggested that at least some of the cytosolic oxidase components exist as a complex. We have now purified such a complex from the cytoplasm of resting neutrophils using an affinity column prepared with an antibody that recognizes the C-terminal decapeptide of p47(phox). Immunoblotting showed that the complex contained both p47(phox) and p67(phox). When supplemented with recombinant p67(phox), the complex displayed considerable activity in a cell-free oxidase-activating system, and even without added p67(phox), the complex could more than double O(2)(-)production in an oxidase-activating system supplemented with suboptimal amounts of cytosol. Isolation of the complex was blocked by preincubating the affinity column with CFSTKRKLASAV, the peptide against which the antibody was raised. On gel filtration, the complex migrated with a molecular weight of 240-300K, similar to that observed with whole neutrophil cytosol. The p47(phox)/p67(phox) ratio in the gel-filtered complex was approximately 1 to 1. These results indicate that in resting neutrophil cytosol, p47(phox) and p67(phox) exist as a complex.