Evolutionary reduction, parallel

Sadler and Johnson [S96) claimed that reverse electron flow involving cytochrome c has not been established for T. neapolitanus and T. thio-parus and proposed the parallel pathways of Figs. 37a and 37b but offered no suggestion as to the source of the NADH. Yamanaka et al. (334) have found multiple cytochromes in T. novellus which they place in series as in Fig. 37c. They proposed that sulfite delivers its electrons to C551 by means of a sulfite. cytochrome c oxidoreductase enzyme. In all of these Thiobadllus species, there is at least one cytochrome c with a reduction potential near -j-280 mV and a molecular weight around 13,000, which probably is an evolutionary homolog of eukaryotic c. 

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