ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Solvophobically driven folding of nonbiological oligomers (1997)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1997-09-20
    Description: In solution, biopolymers commonly fold into well-defined three-dimensional structures, but only recently has analogous behavior been explored in synthetic chain molecules. An aromatic hydrocarbon backbone is described that spontaneously acquires a stable helical conformation having a large cavity. The chain does not form intramolecular hydrogen bonds, and solvophobic interactions drive the folding transition, which is sensitive to chain length, solvent quality, and temperature.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nelson, J C -- Saven, J G -- Moore, J S -- Wolynes, P G -- PHS 1 S10 RR10444-01/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1997 Sep 19;277(5333):1793-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, IL 61801, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9295264" target="_blank"〉PubMed〈/a〉
    Keywords: Acetonitriles ; Acetylene/*analogs & derivatives/chemistry ; Chemistry, Physical ; Chloroform ; Hydrogen Bonding ; Magnetic Resonance Spectroscopy ; Models, Molecular ; *Molecular Conformation ; Physicochemical Phenomena ; Polymers/*chemistry ; Solubility ; Solvents ; Spectrophotometry, Ultraviolet ; Temperature ; Thermodynamics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Classical and quantum continuum percolation with hard core interactions (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 6153-6159 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We study the classical and quantum percolation of spheres in a three-dimensional continuum. Each sphere has an impenetrable hard core of diameter σ, and two spheres are considered to be directly connected if the distance between their centers is less than d. We calculate the critical percolation density as a function of σ/d. In the classical problem this is the density ρc at which an infinite cluster of connected spheres first forms. In the quantum problem, we study a tight-binding model where the hopping matrix element between two spheres is nonzero only if they are directly connected. In this case the critical density ρq is the density at which the eigenstates of the Hamiltonian first become extended. Our method uses Monte Carlo simulation and finite-size scaling techniques, and for the quantum problem, the concept of quantum connectivity. We find that both ρc and ρq exhibit nonmonotonic behavior as a function of σ/d. We also find that for all values of σ/d, ρq〉ρc, although the ratio of the thresholds decreases with increasing σ/d. We argue that a better understanding of this ratio is obtained by considering the average coordination number. We speculate about the nature of both classical and quantum percolation as σ/d approaches 1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460401
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A molecular theory of the line shape: Inhomogeneous and homogeneous electronic spectra of dilute chromophores in nonpolar fluids (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 4391-4402 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Kubo's stochastic theory of the spectral line shape provides an elegant phenomenological description of inhomogeneous and homogeneous broadening and the transition between the two. This theory has been used profitably in the analysis of many experiments. In this paper we attempt to provide a microscopic foundation for the Kubo model by developing a completely molecular theory of the line shape. For definiteness we focus on the optical line shape of dilute chromophores in nonpolar fluids. Many of the features of the Kubo theory are found in the molecular theory; indeed, the molecular theory produces microscopic expressions involving the solvent structure and dynamics for Kubo's phenomenological parameters, and provides some justification for the Gaussian assumption in the stochastic theory. On the other hand, the molecular theory produces a transition frequency time-correlation function that is distinctly nonexponential, in contrast to the exponential assumption of the Kubo theory, and it is found that this nonexponentiality is necessary for the accurate description of line shapes in the regime intermediate between inhomogeneous and homogeneous broadening. For a model of Lennard-Jones particles the molecular theory is compared with molecular dynamics computer simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466092
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of protein folding: The dynamics of globally connected rough energy landscapes with biases (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 11037-11043 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We study relaxation within a biased rough energy landscape as a means of investigating protein folding kinetics. The energies of the conformational states of the protein are taken to be random variables. The degree of similarity of each state with the native is described by an order parameter ρ. The energy is, on average, a decreasing function of ρ, in line with the principle of minimal frustration. The limiting case model described here has global connectivity. There are no restrictions on the change in order parameter in the elementary moves through conformational space. The folding kinetics vary as a function of both the energy gap between the folded and unfolded states and the roughness of the energy landscape. This model yields curved Arrhenius plots that are qualitatively similar to those seen in experiments and in simulations of protein folding. We show that in globally connected models, the Laplace transformed concentrations of species obey a frequency dependent generalization of the law of mass action. We show that when states with intermediate degrees of ordering are included in a globally connected model, one obtains much the same qualitative behavior as some experiments that are often used to justify the existence of specific intermediates along a sequential pathway even though there is no such path in the model. Also we show that for short times, populations of ensembles of configurations are dominated by entropic considerations: an observation in harmony with studies on initial events in folding based on more detailed models. Thus, we believe that this model sheds light on the interpretation of experiments that probe protein folding kinetics. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467855
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Molecular theory of electronic spectroscopy in nonpolar fluids: Ultrafast solvation dynamics and absorption and emission line shapes (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2129-2144 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a theory of time- and frequency-domain spectroscopy of a dilute nonpolar solute in a nonpolar liquid or supercritical fluid solvent. The solute and solvent molecules are assumed to interact with isotropic pair potentials. These potentials, together with the solute and solvent masses, are the only input in the theory. We arrive at expressions for the absorption and emission line shapes, which include the possibility of motional narrowing, and for the time-resolved fluorescence and transient hole-burning observables, by assuming that the solute's fluctuating transition frequency describes a Gaussian process. These expressions depend only on the average and variance of the transition frequency distributions in absorption and emission and on the normalized frequency fluctuation time-correlation functions. Within our formalism the former are obtained from the solute-solvent and solvent-solvent radial distribution functions, which are calculated using integral equations. The time-correlation functions involve the time-dependent solute-solvent Green's function. Its solution depends upon the solute and solvent diffusion constants, which in turn are determined from the radial distribution functions. The theory compares favorably with computer simulation results of the same model. We then investigate the dependence of the various spectroscopic observables on the solvent density, the temperature, and the difference between the ground- and excited-state solute's pair interaction with the solvent molecules. For example, since our theory for the time-correlation functions captures both their short- and long-time behavior, we can see how the crossover from inertial to diffusive dynamics depends on these variables. Our results are similar to a variety of experiments on solutes in both nonpolar and polar solvents. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473144
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    facet.materialart.
    Unknown
    Classical and quantum continuum percolation with hard core interactions (1991)
    American Institute of Physics
    Details
    Publication Date: 1991-05-01
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    Computational design of a protein crystal (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-04-25
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Computational design of a protein crystal [Chemistry] (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-05-09
    Description: Protein crystals have catalytic and materials applications and are central to efforts in structural biology and therapeutic development. Designing predetermined crystal structures can be subtle given the complexity of proteins and the noncovalent interactions that govern crystallization. De novo protein design provides an approach to engineer highly complex nanoscale molecular structures, and often the positions of atoms can be programmed with sub-Å precision. Herein, a computational approach is presented for the design of proteins that self-assemble in three dimensions to yield macroscopic crystals. A three-helix coiled-coil protein is designed de novo to form a polar, layered, three-dimensional crystal having the P6 space group, which has a “honeycomb-like” structure and hexameric channels that span the crystal. The approach involves: (i) creating an ensemble of crystalline structures consistent with the targeted symmetry; (ii) characterizing this ensemble to identify “designable” structures from minima in the sequence-structure energy landscape and designing sequences for these structures; (iii) experimentally characterizing candidate proteins. A 2.1 Å resolution X-ray crystal structure of one such designed protein exhibits sub-Å agreement [backbone root mean square deviation (rmsd)] with the computational model of the crystal. This approach to crystal design has potential applications to the de novo design of nanostructured materials and to the modification of natural proteins to facilitate X-ray crystallographic analysis.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Computationally designed peptides for self-assembly of nanostructured lattices (2016)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2016-09-11
    Description: Folded peptides present complex exterior surfaces specified by their amino acid sequences, and the control of these surfaces offers high-precision routes to self-assembling materials. The complexity of peptide structure and the subtlety of noncovalent interactions make the design of predetermined nanostructures difficult. Computational methods can facilitate this design and are used here to determine 29-residue peptides that form tetrahelical bundles that, in turn, serve as building blocks for lattice-forming materials. Four distinct assemblies were engineered. Peptide bundle exterior amino acids were designed in the context of three different interbundle lattices in addition to one design to produce bundles isolated in solution. Solution assembly produced three different types of lattice-forming materials that exhibited varying degrees of agreement with the chosen lattices used in the design of each sequence. Transmission electron microscopy revealed the nanostructure of the sheetlike nanomaterials. In contrast, the peptide sequence designed to form isolated, soluble, tetrameric bundles remained dispersed and did not form any higher-order assembled nanostructure. Small-angle neutron scattering confirmed the formation of soluble bundles with the designed size. In the lattice-forming nanostructures, the solution assembly process is robust with respect to variation of solution conditions (pH and temperature) and covalent modification of the computationally designed peptides. Solution conditions can be used to control micrometer-scale morphology of the assemblies. The findings illustrate that, with careful control of molecular structure and solution conditions, a single peptide motif can be versatile enough to yield a wide range of self-assembled lattice morphologies across many length scales (1 to 1000 nm).
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Molecular theory of electronic spectroscopy in nonpolar fluids: Ultrafast solvation dynamics and absorption and emission line shapes (1997)
    American Institute of Physics
    Details
    Publication Date: 1997-02-08
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...