Current-voltage characteristics of seven-helix proteins from a cubic array of amino acids

Abstract

The electrical properties of a set of seven-helix transmembrane proteins, whose space arrangement (3d structure) is known, are investigated by using regular arrays of the amino acids. These structures, specifically cubes, have topological features similar to those shown by the chosen proteins. The theoretical results show a good agreement between the predicted current-voltage characteristics obtained from a cubic array and those obtained from a detailed 3D structure. The agreement is confirmed by available experiments on bacteriorhodopsin. Furthermore, all the analyzed proteins are found to share the same critical behaviour of the voltage-dependent conductance and of its variance. In particular, the cubic arrangement evidences a short plateau of the excess conductance and its variance at high voltages. The results of the present investigation show the possibility to predict the I-V characteristics of multiple-protein sample even in the absence of a detailed knowledge of their 3D structure.

Hierarchy and Assortativity as New Tools for Binding-Affinity Investigation: The Case of the TBA Aptamer-Ligand Complex

“…*Corresponding Authors: eleonora.alfinito@unisalento.it rosella.cataldo@unisalento.it We distinguish among the resistance of TBA, by using the same notation of Sec.2.1:  in the native state (a), hereafter called rnat ;  in the active state (b), hereafter called ract ;  complexed (c), hereafter called rcom. This procedure allows for the calculation of the capacitance and resistance variation of a single as well as of a sample of macromolecules [14,33,34]. As expected, the results depend on the value of RC, which, in turn, is related to the value of the macromolecule free energy [27,34,35].…”

“…This procedure allows for the calculation of the capacitance and resistance variation of a single as well as of a sample of macromolecules [14,33,34]. As expected, the results depend on the value of RC, which, in turn, is related to the value of the macromolecule free energy [27,34,35]. Therefore, a complete information is obtained by analyzing the interaction spectra, i.e.…”

Odorant Binding Changes the Electrical Properties of Olfactory Receptors at the Nanoscale

“…These models are generally based on equivalent impedance networks trying to link the dipoles and charges of the backbone and side chains of the receptor in its native and activated state, with the experimental results obtained. 13,14 Here, we have determined directly the nanoscale electrical properties of human OR hOR1A1 in the presence of its cognate ligand dihydrojasmone, using electrochemical scanning tunneling microscopy (EC-STM) under bipotentiostatic control. In particular, we have measured current-voltage (I-V), current-time (I-t) and current-distance (I-z) characteristics of the receptor immobilized in a fixed orientation in a near-physiological environment.…”