Аннотация:Accumulation of biologically available energy by the living organisms during respiration occurs initially in the inner mitochondrial or prokaryotic cytoplasm membranes in the form of proton-motive-force. Three decades ago a sodium (Na+)-pumping complex, i.e. the Na+-motive NADH-quinone-oxidoreductase (NQR), was revealed in the respiratory chain in coupling site I of some aerobic alkaliphilic bacteria (1). The possible existence of a Na+-motive complex IV in alkaliphilic bacteria was assumed by V. Skulachev 30 years ago (2). However, during the last 30 years, NQR was the only component of respiratory chains in aerobic bacteria known to accumulate energy in the form of sodium-motive-force. The other segments of respiratory chain and particularly complex IV, which converts the large portion of the utilizable energy provided during respiration, were believed to be H+-motive. Recently, our group demonstrated that the first oxygen-reducing Na+-pump, i.e. complex IV, operates in the respiratory chain of extremely alkaliphilic bacteria.
References:
1. Tokuda H, Unemoto T: Na+ is translocated at NADH: quinone oxidoreductase segment in the respiratory chain of Vibrio alginolyticus. 1984 J Biol Chem 259(12):7785-7790.
2. Skulachev VP: Sodium bioenergetics. 1984 TiBS 9(11):483-485.