Characterization of cytochrome c from Nitrobacter Agilis

Chemolithoautotrophic Bacteria

“…The reduction step of molecular oxygen catalyzed by cytochrome c oxidase proceeds rapidly, because E m,7.0 of H 2 O/O 2 system is +0.82 V and is very much higher than that of cytochrome c-550. The author and his coworkers purifi ed from the bacterium all the components that seemed to participate in nitrite oxidation; cytochrome a 1 c 1 (nitrite oxidoreductase) (Tanaka et al, 1983), soluble cytochrome c-550 [cytochrome c550(s)] (Ketchum et al, 1969;Yamanaka et al, 1982), membrane bound cytochrome c-550 [cytochrome c-550(m)] (Nomoto et al, 1993), and cytochrome aa 3 (cytochrome c oxidase) (Yamanaka et al, 1979a(Yamanaka et al, , 1981a. Previously, the potential of the cytoplasm membrane was thought to be necessary for the reduction step of cytochrome c-550 with nitrite (Cobley, 1976), because the ionophore diminished the nitrite oxidation rate by Nitrobacter winogradskyi (Cobley, 1984).…”

“…Cytochrome c-550(s) was partially purifi ed by Ketchum et al (1969). Afterward it was purifi ed to an electrophoretically homogeneous state , and its complete amino acid sequence was determined .…”

Cytochromes

“…Cytochromes C are isolated and purified from several autotrophic bacteria: from Thiobacillus novellus , T. concretivorus (Moriarty and Nicholas, 1966), Thiobacillus neapolitanus* (Trudinger, 1961), T. thioparus (Klimek et al, 1956), T. denitnficans (Aubert et al, 1958); T. thiooxidans (Tano et al, 1968), Citrobacter agilis (Ketchum et al, 1969), and Nitrosomonas europaea (Yamanaka and Shinra, 1971).…”

“…Cytochrome c (550, Citrobacter agilis) is a basic protein and shows an absorption spectrum similar to that of the mammalian-type cytochrome c (Ketchum et al, 1969).…”

The nitrite oxidizing system of Nitrobacter winogradskyi

“…The oxidation of NO 2 through a cytochrome system brings forward a problem; since the Em, 8 of NOf/NO 3 (+0.360 V) [7] is higher than that of cytochrome c-550 of this bacterium (+ 0.282 V) [8], the electron transport from NO{ to cytochrome c-550 should not occur easily. Indeed, Aleem [3,7] has indicated that the reduction of cytochrome c (horse) by NO 2 is very difficult.…”