ATP hydrolysis and synthesis by the membrane-bound ATP synthetase complex of Methanobacterium thermoautotrophicum.
The membrane-bound ATP synthetase complex of Methanobacterium thermoautotrophicum showed maximum activity for ATP hydrolysis at pH 8, at temperatures between 65 and 70 degrees C, and at an ATP-Mg2+ ratio of 0.5. Anaerobic conditions were not prerequisite for enzyme activity. The enzyme showed a Km value for ATP of 2 mM, and activity was Mg2+ dependent; Mn2+, Co2+, Ca2+, and Zn2+ could replace Mg2+ to some extent. Other nucleoside triphosphates could be hydrolyzed. N,N'-dicyclohexylcarbodiimide inhibited ATP hydrolysis. A proton-motive force, artificially imposed by a pH shift or valinomycin, resulted in ATP synthesis in whole cells. The ATP synthetase complex of the thermophilic methanogenic bacterium is similar to those described in aerobic and anaerobic microorganisms.
D000244:Adenosine Diphosphate; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D019605:Euryarchaeota / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D013696:Temperature
D009097:Multienzyme Complexes; D004024:Dicyclohexylcarbodiimide; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D000251:Adenosine Triphosphatases; D008274:Magnesium