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  • 1
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    JBIC 3 (1998), S. 196-200 
    ISSN: 1432-1327
    Keywords: Key words Electron transfer ; Pi-way ; Tunneling pathway ; Hole transfer ; Tunneling energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Electron transfer in DNA has been investigated for decades, but recent experiments highlight our limited fundamental understanding of these processes. Modern electron transfer theory may help to address some of the open mechanistic issues. We summarize and analyze the results of recent experiments from a theoretical perspective. Future research directions are suggested that might help to establish the molecular mechanism(s) for long-range DNA electron transfer.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    JBIC 2 (1997), S. 378-386 
    ISSN: 1432-1327
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Protein-mediated electronic interactions facilitate biological electron transfer (ET) reactions. Theory and experiment are being used extensively to establish atomic-scale descriptions of these reactions. The last 20 years have seen a progression of descriptions ranging from square barrier protein approximations to tunneling Pathway models, and recently to valence orbital Hamiltonian methods. Pathway connectivity, reflecting a protein's secondary and tertiary motif, is predicted (and was recently confirmed) to determine the ET rate. A critical challenge now is to extract from more detailed orbital descriptions, with millions of interaction elements between orbitals, predictions of how primary sequence and folding-induced contacts influence electron transfer rates. Electron transfer contact maps reduce the orbital interaction information in a manner that allows ready interpretation in the context of protein motifs and mutations. We discuss these modern models for protein ET and the reduced views that are being derived from them.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-6881
    Keywords: Tunneling pathways ; protein electron transfer ; donor-acceptor interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The simplest views of long-range electron transfer utilize flat one-dimensional barrier tunneling models, neglecting structural details of the protein medium. The pathway model of protein electron transfer reintroduces structure by distinguishing between covalent bonds, hydrogen bonds, and van der Waals contacts. These three kinds of interactions in a tunneling pathway each have distinctive decay factors associated with them. The distribution and arrangement of these bonded and nonbonded contacts in a folded protein varies tremendously between structures, adding a richness to the tunneling problem that is absent in simpler views. We review the pathway model and the predictions that it makes for protein electron transfer rates in small proteins, docked proteins, and the photosynthetic reactions center. We also review the formulation of the protein electron transfer problem as an effective two-level system. New multi-pathway approaches and improved electronic Hamiltonians are described briefly as well.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1056-8700
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
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  • 7
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    In:  Other Sources
    Publication Date: 2011-08-24
    Description: The key to understanding the mechanisms of many important biological processes such as photosynthesis and respiration is a better understanding of the electron transfer processes which take place between metal atoms (and other groups) fixed within large protein molecules. Research is currently focused on the rate of electron transfer and the factors that influence it, such as protein composition and the distance between metal atoms. Current models explain the swift transfer of electrons over considerable distances by postulating bridge-mediated tunneling, or physical tunneling pathways, made up of interacting bonds in the medium around and between donor and acceptor sites. The program PATHWAYS is designed to predict the route along which electrons travel in the transfer processes. The basic strategy of PATHWAYS is to begin by recording each possible path element on a connectivity list, including in each entry which two atoms are connected and what contribution the connection would make to the overall rate if it were included in a pathway. The list begins with the bonded molecular structure (including the backbone sequence and side chain connectivity), and then adds probable hydrogen bond links and through-space contacts. Once this list is completed, the program runs a tree search from the donor to the acceptor site to find the dominant pathways. The speed and efficiency of the computer search offers an improvement over manual techniques. PATHWAYS is written in FORTRAN 77 for execution on DEC VAX series computers running VMS. The program inputs data from four data sets and one structure file. The software was written to input BIOGRAF (old format) structure files based on x-ray crystal structures and outputs ASCII files listing the best pathways and BIOGRAF vector files containing the paths. Relatively minor changes could be made in the input format statements for compatibility with other graphics software. The executable and source code are included with the distribution. The main memory requirement for execution is 2.6 Mb. This program is available in DEC VAX BACKUP format on a 9-track 1600 BPI magnetic tape (standard distribution) or on a TK50 tape cartridge. PATHWAYS was developed in 1988. PATHWAYS is a copyrighted work with all copyright vested in NASA. DEC, VAX, VMS, and TK50 are trademarks of Digital Equipment Corporation. BIOGRAF is a trademark of Molecular Simulations, Inc., Sunnyvale, CA.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: NPO-18139
    Format: text
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  • 8
    Publication Date: 2011-08-19
    Description: Conjugated organic molecules with electron-donating and -accepting moieties can exhibit large electronic second-order nonlinearities, or first hyperpolarizabilities, beta. The present two-state, four-orbital independent-electron analysis of beta leads to the prediction that its absolute value will be maximized at a combination of donor and acceptor strengths for a given conjugated bridge. Molecular design strategies for beta optimization are proposed which give attention to the energetic manipulations of the bridge states. Experimental results have been obtained which support the validity of this approach.
    Keywords: OPTICS
    Type: Science (ISSN 0036-8075); 252; 103-106
    Format: text
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  • 9
    Publication Date: 2015-09-02
    Description: Proteins catalyze crucial reactions via unstable, high-energy chemical intermediates. In the absence of physiological substrates, activated redox cofactors become ticking time bombs, capable of producing oxidative damage to the protein. In PNAS, Gray and Winkler (1) propose that chains of tryptophan (Trp) and tyrosine (Tyr) residues may serve as escape...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 10
    Publication Date: 2014-07-16
    Description: Biological electron-transfer (ET) reactions are typically described in the framework of coherent two-state electron tunneling or multistep hopping. However, these ET reactions may involve multiple redox cofactors in van der Waals contact with each other and with vibronic broadenings on the same scale as the energy gaps among the species....
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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