SYNTHETIC PEPTIDES CORRESPONDING TO VARIOUS HYDROPHILIC REGIONS OF THE LARGE SUBUNIT OF CYTOCHROME B(558) INHIBIT SUPEROXIDE GENERATION IN A CELL-FREE SYSTEM FROM NEUTROPHILS

Cytochrome b(558) is a component of the superoxide-generating system i n neutrophils and plays key roles in both the assembly of a functional complex with cytosolic proteins and shuttling an electron from NADPH to molecular oxygen. To determine the role of predicted hydrophilic do mains of gp91-phox, a glycosylated subunit of the cytochrome, we synth esized peptides corresponding to the regions and tested whether they a ffected superoxide generation in the cell-free system obtained from hu man neutrophils. Among twelve peptides tested, six peptides, four of w hich correspond to previously unreported regions, inhibited superoxide generation in the cell-free system. All of the active peptides were e ffective when added to the system before activation with sodium dodecy l sulfate. Four peptides, including two peptides corresponding to two newly identified regions, inhibited the translocation of the cytosolic components, p47-phox and p67-phox. The extent of inhibition on transl ocation of these components varied depending on the peptide used. (C) 1997 Academic Press.