Some general aspects of ion interactions with the channel pore

Abstract

Generalized mechanisms of ion selectivity in KcsA, Na_vRh and Ca_v (L-type) cation channels are systematically explored. We give unambiguous exposition explaining why and how the above listed ion-channels can be highly selective, and yet has a conductance of the order of one million ions per second, or higher. We will properly identify and prove the correct quantum mechanical type interactions that are responsible for the high selectivity of a particular ion in an ion channel. The above mechanisms consist of five conditions that can be directly associated to these parameters—(i) dehydration energy, (ii) concentration of the ‘correct’ ions (iii) Ramachandran attraction, (iv) pore and ion sizes, and indirectly to (v) thermodynamic stability and (vi) the ‘knock-on’ assisted permeation.