Autocatalytic cooperativity and self-regulation of ATPase pumps in membrane active transport.
We investigate the effect of autocatalysis on the conformational changes of membrane pumps during active transport driven by ATP. The translocation process is described by means of an alternating access model. The usual kinetic scheme is extended by introducing autocatalytic steps and allowing for dynamic formation of enzyme complexes. The usual features of cooperative models are recovered, i.e., sigmoid shapes of flux versus concentration curves. We show also that two autocatalytic steps lead to a mechanism of inhibition by the substrate as experimentally observed for some ATPase pumps. In addition, when the formation of enzyme complexes is allowed, the model exhibits a multiple stationary states regime, which can be related to a self-regulation mechanism of the active transport in biological systems.
Weissmüller
G
G
Centro Brasileiro de Rua Xavier Siguad 150, Rio de Janeiro, Brazil.
Bisch
P M
PM
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001665:Binding Sites; D001693:Biological Transport, Active; D002384:Catalysis; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D007700:Kinetics; D008432:Mathematical Computing; D008954:Models, Biological
D000251:Adenosine Triphosphatases