Lactate oxidation system was investigated in Acetobacter suboxydans, which was found to have cytochromes a and b, but no cytochrome c. Haemoprotein 558 was also found to exist. Carbon monoxide inhibited the lactate oxidation in the dark but not in the light. WARBURG'S partition constant was estimated to be 7. Addition of haemoprotein 558 noticeably enhanced the oxygen uptake by the LDH preparation, which was obtained from bacterial cells and partially purified. Haemoprotein 558 has protohaem as its prosthetic group. Not only its absorption spectrum is reminiscent of that of peroxidase, but it also shows peroxidase-like reactivity with some ligands with a few exceptions. Ferrohaemoprotein 558 reacts with oxygen, forming, at first, a complex, which has its SORET absorption peak at 423 mμ. The absorption maximum then shifts to 417 mμ, indicating a transformation to another compound. One of these two products is likely to be the oxygenated ferro-haemoprotein 558. The mutual transformation between cytochrome B and haemoprotein 558 is discussed.
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Hidekazu Iwasaki (1966) studied this question.