A cytochrome c peroxidase isolated from Thiobacillus novellus

A cytochrome c peroxidase (ferrocytochrome c :H 2 O 2 oxidoreductase, EC 1.11.1.5) was isolated and highly purified from Thiobacillus novellus , and its properties were studied. The enzyme has haem c as the prosthetic group, and shows a peak at 398 nm in the oxidized form and peaks at 415, 520 and 550 nm in the reduced form. It peroxidatically oxidizes the reduced form of cytochrome c (550, Thiobacillus novellus ) and mammalian-type cytochromes c but does not react or reacts very poorly with bacterial c -type cytochromes such as cytochrome c (551, Pseudomonas aeruginosa ), cytochrome c (552, Nitrosomonas europaea ) and cytochrome c (555, Chlorobium thiosulfatophilum ). One mole of the enzyme oxidizes peroxidatically 2450 moles of tuna ferrocytochrome c per min at pH 8.5 and at 18 °C. The peroxidase reaction catalysed by the enzyme is strongly inhibited by cyanide and azide.