A kinetic study of the rat liver adenosine kinase reverse reaction.
Adenosine kinase is an enzyme catalyzing the reaction: adenosine + ATP --> AMP + ADP. We studied some biochemical properties not hitherto investigated and demonstrated that the reaction can be easily reversed when coupled with adenosine deaminase, which transforms adenosine into inosine and ammonia. The overall reaction is: AMP + ADP --> ATP + inosine + NH(3). The exoergonic ADA reaction shifts the equilibrium and fills the energy gap necessary for synthesis of ATP. This reaction could be used by cells under particular conditions of energy deficiency and, together with myokinase activity, may help to restore physiological ATP levels.
Vannoni
D
D
Dipartimento di Medicina Interna, Sc. Endocrino-Metaboliche e Biochimica, Università di Siena, Siena, Italy. vannoni@unisi.it
Giglioni
S
S
Santoro
A
A
Aceto
E
E
Marinello
E
E
Leoncini
R
R
D000241:Adenosine / Q000378:metabolism; D000243:Adenosine Deaminase / Q000378:metabolism; D000248:Adenosine Kinase / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D007288:Inosine / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D051381:Rats; D013379:Substrate Specificity
D007288:Inosine; D000641:Ammonia; D000248:Adenosine Kinase; D000243:Adenosine Deaminase; D000241:Adenosine