Interaction of Pseudomonas cytochrome cd1 with the cytoplasmic membrane

Labelling with ferritin-conjugated antibody shows that Pseudomonas cytochrome cd1 is associated with the inner surface of the cytoplasmic membrane. Cytochrome cd1 is however, enriched to the soluble fraction obtained after destruction of Pseudomonas spheroplasts. Comparison of the respiratory nitrite reductase activities, due to this cytochrome, between different cellular fractions and the purified enzyme shows that while the kinetic pattern and the temperature dependence of the activity remain almost the same the molecular activity is enhanced when the enzyme is released from cells. A new assay of respiratory nitrite reductase was developed in this study. The method is based on determination of the stoichiometrical proton consumption accompanying nitrite reduction.