Polypeptides in alpha-helix conformation perform as diodes.
Molecules that resemble a semiconductor diode depletion zone are those with an intrinsic electric dipole, which were suggested as potential electronic devices. However, so far, no single molecule has met such a goal because any electron donor-acceptor linker strongly diminishes any possibility of diode behavior. We find an intrinsic diode behavior in polypeptides such as poly(L-alanine) and polyglycine in alpha-helix conformation, explained in terms of molecular orbital theory using ab initio methods. The application of an antiparallel electric field with respect to the molecular dipole yields a gradual increase in current through the junction because the valence and conduction orbitals approach each other reducing their gap as the bias increases. However, a parallel field makes the gap energy increase, avoiding the pass of the electrons.
Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA.
Dahiyana
D
Cristancho
Jorge M
JM
Seminario
D004553:Electric Conductivity; D004583:Electrons; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012666:Semiconductors
D010455:Peptides; C019529:polyalanine; C011080:polyglycine