inducible alternate terminal oxidase in Euglena gracilis mitochondria

• Published in: The Journal of biological chemistry Vol. 245; no. 1; pp. 58 - 70
• Main Authors: Sharpless, T.K, Butow, R.A
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 10.01.1970
• Subjects: Adenine Nucleotides - pharmacology; Antimycin A - pharmacology; Biological Sciences; Carbon Isotopes; Centrifugation, Density Gradient; Culture Media; Cyanides - pharmacology; Electron Transport; Enzyme Activation; Enzyme Induction; Ethanol - pharmacology; Euglena - enzymology; Fumarates - biosynthesis; Hydrogen Peroxide - biosynthesis; Kinetics; Malates - biosynthesis; Mitochondria - drug effects; Mitochondria - enzymology; NAD - metabolism; Phenylhydrazines - pharmacology; Potassium; Spectrophotometry; Succinate Dehydrogenase - antagonists & inhibitors; Succinate Dehydrogenase - biosynthesis; Water - biosynthesis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)63422-2

1. A new succinoxidase activity has been found in mitochondria of Euglena gracilis grown in the presence of either ethanol or succinate and antimycin. 2. The new oxidase activity is characterized by its insensitivity to antimycin and KCN and by its marked stimulation on addition of AMP. The principal products of succinate oxidation are malate, fumarate, and water. Tests for the formation of H 2 O 2 have been negative. 3. Oxidation of NADH can be channeled through this terminal oxidase as indicated by an insensitivity to KCN and stimulation by AMP. Cyanide-insensitive oxidation of NADH is linked to phosphorylation, whereas succinate oxidation is not. These findings suggest that the new terminal oxidase is associated with the electron transport chain in the region of succinate dehydrogenase. 4. It is suggested that the alternate oxidase may account for the high respiratory rates known to accompany induction of glyoxylate cycle enzymes in Euglena .