Entropy hysteresis and nonequilibrium thermodynamic efficiency of ion conduction in a voltage-gated potassium ion channel.
Here we have studied the nonequilibrium thermodynamic response of a voltage-gated Shaker potassium ion channel using a stochastic master equation. For a constant external voltage, the system reaches equilibrium indicated by the vanishing total entropy production rate, whereas for oscillating voltage the current and entropy production rates show dynamic hysteretic behavior. Here we have shown quantitatively that although the hysteresis loop area vanishes in low and high frequency domains of the external voltage, they are thermodynamically distinguishable. In the very low frequency domain, the system remains close to equilibrium, whereas at high frequencies it goes to a nonequilibrium steady state (NESS) associated with a finite value of dissipation function. At NESS, the efficiency of the ion conduction can also be related with the nonlinear dependence of the dissipation function on the power of the external field. Another intriguing aspect is that, at the high frequency limit, the total entropy production rate oscillates at NESS with half of the time period of the external voltage.
SN Bose National Centre For Basic Sciences Block JD, Sector III, Salt Lake, Kolkata 700098, India.
Biswajit
B
Das
Kinshuk
K
Banerjee
Gautam
G
Gangopadhyay
D000818:Animals; D001703:Biophysics / Q000379:methods*; D006801:Humans; D007477:Ions / Q000378:metabolism*; D007700:Kinetics; D008390:Markov Chains; D015233:Models, Statistical; D009991:Oscillometry; D016012:Poisson Distribution; D011188:Potassium / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology*; D011336:Probability; D017434:Protein Structure, Tertiary; D013269:Stochastic Processes; D013816:Thermodynamics; D013997:Time Factors
D007477:Ions; D024642:Potassium Channels, Voltage-Gated; D011188:Potassium