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Influence of Ca2+ Oscillatory Influx on Membrane Ca2+-ATPase Activity: a Kinetic Model

B. N. Goldstein*, A. A. Mayevsky, and D. T. Zakrjevskaya

Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; fax: (7-0967) 79-0553; E-mail: goldstein@iteb.ru

* To whom correspondence should be addressed.

Received April 6, 2004; Revision received May 11, 2004
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.
KEY WORDS: Ca2+-ATPase, oscillations, signal coding, kinetic model