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Spectral evidence for the existence of a 2nd cytochrome o in whole cells of vitreoscilla






Journal of Biological Chemistry 258(22): 13768-13771

Spectral evidence for the existence of a 2nd cytochrome o in whole cells of vitreoscilla

Cytochrome o, a protoheme IX pigment, is proposed as the terminal oxidase of the filamentous bacterium, Vitroscilla. Aerobic and anaerobic photolysis of CO-liganded whole cells demonstrated the presence of a second CO-reactive pigment, cytochrome o' At temperatures lower than -100.degree. C, anaerobic photolysis dissociated only .apprx. 25% of the total CO-liganded components to reveal the unliganded cytochrome o'. At these temperatures, the photolysis of cytochrome o could not be demonstrated. At warmer temperatures, recombination of CO with the reduced cytochrome o' occurred with an apparent energy of activation of 5.8 kcol/mol. Aerobic photolysis of whole cells demonstrated 2 O-bound intermediates. At temperatures lower than -95.degree. C, a spectrally distinct compound with absorption maxima at 428, 534 and 564 nm appeared (form I'); the apparent second order rate constant (k+1) for the formation of this intermediate was 9.1 M-1 s-1, the reverse rate (k-1) was 9.9 .times. 10-5 s-1 and the equilibrium constant (Kd) was 1.1 .times. 10-5 M. This O intermediate of cytochrome o' is spectrally and kinetically similar to the O intermediate of cytochrome o seen in Escherichia coli. At temperatures warmer than -90.degree. C, photolysis of aerobic samples resulted in the immediate formation of a second O-bound intermediate (form I) with absorption maxima at 422, 534 and 564 nm. This second intermediate results from the binding of O to the cytochrome o (oxygenated cytochrome o). These data support the proposal that whole cells of Vitreoscilla contain 2 alternative pathways of electron transport, one terminating with cytochrome o and the other with cytochrome o'.


Accession: 006459682



Related references

DeMaio, R.A.; Webster, D.A.; Chance, B., 1983: Spectral evidence for the existence of a second cytochrome o in whole cells of Vitreoscilla. Cytochrome o, a protoheme IX pigment, has been proposed as the terminal oxidase of the filamentous bacterium, Vitreoscilla. Aerobic and anaerobic photolysis of CO-liganded whole cells demonstrated the presence of a second CO-reactive pigment, cyto...

Webster, D.A.; Liu, C.Y., 1974: Reduced nicotinamide adenine dinucleotide cytochrome o reductase associated with cytochrome o purified from Vitreoscilla. Evidence for an intermediate oxygenated form of cytochrome o. Journal of Biological Chemistry 249(13): 4257-4260

Kim, S.K.; Stark, B.C.; Webster, D.A., 2005: Evidence that Na+-pumping occurs through the D-channel in Vitreoscilla cytochrome bo. The operon (cyo) encoding the Na+-pumping respiratory terminal oxidase (cytochrome bo) of the bacterium Vitreoscilla was transformed into Escherichia coli GV100, a deletion mutant of cytochrome bo. This was done for the wild type operon and five m...

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Webster, D.A.; Orii, Y., 1977: Oxygenated Cytochrome o. An active intermediate observed in whole cells of Vitreoscilla. The oxygenerated form of cytochrome o can be readily observed in whole cell suspensions of Vitreoscilla because it is the predominant steady state form of the cytochrome in respiring cells. When oxygen is introduced to an anaerobic suspension of c...

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Peschek G.A., 1981: Spectral properties of a cyanobacterial cytochrome c oxidase evidence for cytochrome aa 3. Membranes isolated from Nostoc sp. strain Mac oxidized NAD(P)H and horse heart ferrocytochrome c in dark reactions inhibited by KCN, NaN3, CO and by anaerobiosis. Reduced minus oxidized difference spectra revealed peaks at 603 and 445 nm which shi...

Orii, Y.; Webster, D.A., 1977: Oxygenated cytochrome o vitreoscilla formed by treating oxidized cytochrome with super oxide anion. Oxygenated cytochrome o can be formed experimentally in 2 ways: (i) by reaction of reduced cytochrome o with O2; or (ii) by reaction of oxidized cytochrome o with superoxide anion [O2-] generated by the action of the xanthine oxidase system. It is...