Vibrational energy transport through a capping layer of appropriately designed peptide helices over gold nanoparticles.
ABSTRACT We design and characterize spherical gold nanoparticles, which are covalently linked to and completely covered by 3(10)-helical peptides. These helices provide a scaffold to place (13)C=O isotope labels at defined distances from the gold surface, which we employ as local thermometers. Probing these reporter groups with transient infrared spectroscopy, we monitor the vibrational energy flow across the peptide capping layer following excitation of the nanoparticle plasmon resonance.
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ABSTRACT: A method is proposed to analyze the intra- and intermolecular vibrational energy flow occurring in biomolecules in solution during relaxation processes. It is based on the assumption that the total energy exchanged between the vibrational modes is minimal and the global process is essentially statistical. This statistical minimum flow method is shown to provide very useful information about the amount and the rate at which energy is transferred between the individual vibrations of the molecule. To demonstrate the performance of the method, an application is made to the relaxation of the amide I mode of N-methylacetamide-d in aqueous D(2)O solution which yields a detailed quantitative description of the process.The Journal of Chemical Physics 11/2011; 135(20):204106. · 3.16 Impact Factor
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ABSTRACT: Allosteric interactions in proteins generally involve propagation of local structural changes through the protein to a remote site. Anisotropic energy transport is thought to couple the remote sites, but the nature of this process is poorly understood. Here, we report the relationship between energy flow through the structure of bovine serum albumin and allosteric interactions between remote ligand binding sites of the protein. Ultrafast infrared spectroscopy is used to probe the flow of energy through the protein backbone following excitation of a heater dye, a metalloporphyrin or malachite green, bound to different binding sites in the protein. We observe ballistic and anisotropic energy flow through the protein structure following input of thermal energy into the flexible ligand binding sites, without local heating of the rigid helix bundles that connect these sites. This efficient energy transport mechanism enables the allosteric propagation of binding energy through the connecting helix structures.Nature Communications 01/2014; 5:3100. · 10.02 Impact Factor
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ABSTRACT: Quantum energy transfer in a chain of two-level (spin) units, connected at its ends to two thermal reservoirs, is analyzed in two limits: (i) in the off-resonance regime, when the characteristic subsystem excitation energy gaps are larger than the reservoirs frequencies, or the baths temperatures are low and (ii) in the resonance regime, when the chain excitation gaps match populated bath modes. In the latter case, the model is studied using a master equation approach, showing that the dynamics is ballistic for the particular chain model explored. In the former case, we analytically study the system dynamics utilizing the recently developed Energy-Transfer Born-Oppenheimer formalism [L.-A. Wu and D. Segal, Phys. Rev. E 83, 051114 (2011)], demonstrating that energy transfers across the chain in a superexchange (bridge assisted tunneling) mechanism, with the energy current decreasing exponentially with distance. This behavior is insensitive to the chain details. Since at low temperatures the excitation spectrum of molecular systems can be truncated to resemble a spin chain model, we argue that the superexchange behavior obtained here should be observed in widespread systems satisfying the off-resonance condition.The Journal of Chemical Physics 12/2011; 135(23):234508. · 3.16 Impact Factor