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Influence of Ca2+ oscillatory influx on membrane Ca2+-ATPase activity: a kinetic model
B N Goldstein1, A A Mayevsky, D T Zakrjevskaya
1Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia. goldstein@iteb.ru
Abstract:
A kinetic model for the membrane Ca2+-ATPase is considered. The catalytic cycle in the model is extended by enzyme auto-inhibition and by oscillatory calcium influx. It is shown that the conductive enzyme activity can be registered as damped or sustained Ca2+ pulses similar to observed experimentally. It is shown that frequency variations in Ca2+ oscillatory influx induce changes of pulsating enzyme activity. Encoding is observed for the signal frequency into a number of fixed levels of sustained pulses in the enzyme activity. At certain calcium signal frequencies, the calculated Ca2+-ATPase conductivity demonstrates chaotic multi-level pulses, similar to those observed experimentally.
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