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  • Title: Carbon monoxide-binding cytochromes in the respiratory chain of the thermophilic bacterium PS3 grown with sufficient or limited aeration.
    Author: Sone N, Kagawa Y, Orii Y.
    Journal: J Biochem; 1983 May; 93(5):1329-36. PubMed ID: 6885725.
    Abstract:
    The effects of aeration on the growth and cytochrome patterns of thermophilic bacterium PS3 were studied; bacteria grown with strong aeration synthesized cytochromes c, b, and aa3, while those grown with low aeration, showing non-exponential growth, synthesized higher amounts of cytochromes c and b including o, and a lower amount of cytochrome a (a3). The CO-difference spectra indicated that the terminal oxidase was cytochrome aa3 for high aeration conditions and the cytochrome o for low aeration conditions. Cytochrome o can be solubilized by Triton X-100 from the membrane fraction of bacteria grown under oxygen-limited conditions. The carbon monoxide complex of cytochrome o, obtained by exposing this extract to CO, was photolyzed and the subsequent rebinding of CO was analyzed; it followed first order kinetics with a rate constant of around 8 s-1 at 25 degrees C. At liquid nitrogen temperature, CO-rebinding did not occur. The CO-difference spectrum of purified cytochrome oxidase sample from the bacteria grown with strong aeration (Sone, N., et al. (1979) FEBS Lett. 106, 39-42) revealed the presence of a small amount of a cytochrome o-like pigment besides cytochrome aa3. Analysis of the CO complexes of these chromophores showed rate constants of 29-30 s-1 for cytochrome aa3 and 35-42 s-1 for the o-like pigment, indicating that the cytochrome o-like pigment contaminating the purified cytochrome oxidase preparation was not typical cytochrome o.
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