Alternative cyanide-resistant oxidase in plant mitochondria: Structure, regulation of activity, and presumable physiological role

Elucidation of the structure and the control over the activity of CN-resistant alternative oxidase (AO) is a major advance in recent studies of plant mitochondria. Evidence under review from the last decade includes AO isolation from Sauromatum gutatum and other plant species, identification and characterization of the primary AO structure, and elucidation of AO topography in the inner mitochondrial membrane. In addition, new mechanisms for regulating AO activity are considered, in particular, AO activation in the presence of a-ketoacids, and the relevant problem of using inhibitors for assessing AO contribution to the respiration of intact plant cells and tissues. Presumable AO participation in plant defense against oxygen stress and in control over the routes of carbohydrate metabolism is also discussed.