Immunocytochemical localization of APS reductase and bisulfite reductase in three species

The localization of APS reductase and bisulfite reductase in Hildenborough and was studied by immunoelectron microscopy. Polyclonal antibodies were raised against the purified enzymes from each strain. Cells fixed with formaldehyde/glutaraldehyde were embedded and ultrathin sections were incubated with antibodies and subsequently labeled with protein A-gold. The bisulfite reductase in all three strains and APS reductase in and were found in the cytoplasm. The labeling of with APS reductase antibodies resulted in a distribution of gold particles over the cytoplasmic membrane region. The localization of the two enzymes is discussed with respect to the mechanism and energetics of dissimilatory sulfate reduction.