Question

what are the enthalpic and entropic contributions to the thermodynamics of potassium ions passing through the KcsA channel?

Answer 1

It has been found by breaking the free energy barriers (for permeation of ions) into its components i.e. enthalpic and entropic that there is an entropic cost for potassium ion permeation across KcsA channel. It has also been found that the channel length dependence of the free energy is dominated by the enthalpy component but for permeation of potassium ions across the barrier it is the entropy component that is dominant i.e entropic cost dominates the ion permeation free energy barrier across KcsA channel. In summary we can say that the dependence of channel length is strongly influenced by the enthalpic component of the free energy but to over come the permeation barrier it is the reduction in system entropy (as the ion passes the channel) which is the major contributor.

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