Modular gating channel and Cole-Moore effect: next-neighbor (Hill-Chen) versus nonrestricted aggregation

Micro- and macrokinetic behavior of the subunit gating channel

“…Simulations of the microkinetics and numerical calculations of the macrokinetics (see also Baumann & Mueller, 1974;Baumann, 1979) on the basis of the concept of a subunit channel give a self-consistent framework for understanding some basic aspects of electrically gated channels in membranes. In terms of the proposed molecular interpretation it appears that, for biological conductance systems without inactivation, the electrically controlled reorientation of the dipolar channel subunit molecules generally is slower than their subsequent assembly into channel-forming aggregates.…”

“…2). This macrokinetic behavior generated by summing the microkinetic simulation results was found to agree reasonably well with the macrokinetic behavior calculated by another method based on an iterative integration of the rate equations (Baumann, 1979). The macrokinetic conductance is calculated by summing the concentration of each conducting aggregate multiplied by its respective channet area in units of tetramer channel area as calculated in the microkinetic case.…”

Experimental evidence consistent with aggregation kinetics in the sodium current of Myxicola giant axons

“…In the previous paper, Baumann (1981) discussed in some detail the unusual kinetic behavior that can result from a particular model in which a reversible, first-order, voltagedependent reaction step (converting inert to active subunits) is followed by a reversible, voltage-independent, step-by-step assembly of active subunit molecules into a channel-forming aggregate (Baumann and Mueller, 1974;Baumann, 1979;Baumann and Easton, 1980). Such a model is attractive in that it specifies a testable physical mechanism for the observed dissociation between ionic and asymmetry currents.…”