Polypeptides in alpha-helix conformation perform as diodes

Cristancho, Dahiyana; Seminario, Jorge M.

doi:doi:10.1063/1.3310387

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Parallel tempering Monte Carlo simulations of lysozyme orientation on charged surfaces

In this work, the parallel tempering Monte Carlo (PTMC) algorithm is applied to accurately and efficiently identify the global-minimum-energy orientation of a protein adsorbed on a surface in a single simulation. When applying the PTMC method to simulate lysozyme orientation on charged surfaces, it is found that lysozyme could easily be adsorbed on negatively charged surfaces with “side-on” and “back-on” orientations. When driven by dominant electrostatic interactions, lysozyme tends to be adso...

Sequence dependent self-assembly of β-peptides: Insights from a coarse-grained model

The sequence-directed self-assembly of amphiphilic β-peptides is studied using Monte Carlo simulations. A phenomenological model is employed where each molecule is modeled as a rigid nanorod with side groups located at positions to mimic globally amphiphilic (GA) and nonglobally amphiphilic (non-GA) isomers of β-peptides. The strength and the range of interactions between side groups are chosen based on the types of residues. The simulations show that the aggregation of β-peptides is sensitive ...

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 α-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.

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INTRODUCTION
METHODOLOGY
RESULTS
CONCLUSIONS

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KEYWORDS and PACS

Keywords

ab initio calculations, electric moments, molecular configurations, molecular electronics, molecular moments, orbital calculations, polymers, semiconductor diodes

PACS

85.65.+h

Molecular electronic devices
31.15.A-

Ab initio calculations
36.20.Hb

Configuration (bonds, dimensions)
85.30.Kk

Junction diodes
33.15.Kr

Electric and magnetic moments (and derivatives), polarizability, and magnetic susceptibility
36.20.Ey

Conformation (statistics and dynamics)

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http://link.aip.org/link/doi/10.1063/1.3310387

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0021-9606 (print)

1089-7690 (online)

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American Institute of Physics

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