Cytosolic factors involved in the activation of NADPH oxidase from guinea pig neutrophils.

Partial purification of the cytosolic factors which are required for the activation of O2- producing enzyme (NADPH oxidase) was performed using guinea pig neutrophils. Three active cytosolic factors were obtained by using the combination of IEC-SP (cation-exchange) and IEC-QA (anion-exchange) HPLC. One factor (termed SP-1e which was adsorbed on IEC-SP column, somewhat activated the NADPH oxidase by itself. The molecular weight of SP-1 was estimated to be approximately 260 kDa. In contrast, the other two factors (termed QA-1 and QA-2, respectively), which were adsorbed on IEC-QA column, did not activate the NADPH oxidase by themselves but activated the enzyme only in the presence of SP-1. When three factors were combined, they activated the oxidase synergistically, and the activity recovered was almost the same as that observed with the unfractionated cytosol. These results suggest that at least three different cytosolic factors are required for the full activation of NADPH oxidase in guinea pig neutrophils.