Affinity Labeling of the Cytosolic and Membrane Components of the Respiratory Burst Oxidase by the 2′,3′-Dialdehyde Derivative of NADPH: Evidence for a Cytosolic Location of the Nucleotide-binding Site in the Resting Cell

Abstract

The 2',3'-dialdehyde of NADPH (NADPH dialdehyde) appears to act as an affinity label toward the respiratory burst oxidase of human neutrophils, inactivating the enzyme by attaching covalently to a residue at its NADPH-binding site. Although the oxidase in activated neutrophils is known to reside in the plasma membrane, our studies showed that in resting neutrophils the NADPH dialdehyde-sensitive component of the enzyme was located in the cytosol. These findings suggest that one of the steps in the activation of the respiratory burst oxidase is the transfer of its NADPH-binding component from the cytosol to the plasma membrane of the cell.