Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The three-dimensional structure of F1-ATPase from beef heart mitochondria was investigated by electron microscopic techniques. The presence of high concentrations of nucleotides is essential for preservation of the quaternary structure. When investigated under such conditions, monodisperse F1-ATPase could not be distinguished from the membrane-bound enzyme. At low resolution, the particle shape resembles an oblate ellipsoid of revolution with an axial ratio of about 2:1. From several lines of evidence (including field micrographs at higher magnifications, Markham rotational analysis, and tilting experiments), two conclusions may be drawn concerning the three-dimensional fine structure of F1-ATPase. 1. At the periphery of the molecule, six globular protein masses are orientated in a way similar to the chair conformation of cyclohexane. This array is interpreted to be made up of an alternating sequence of alpha and beta subunits. 2. Part of the central space is occupied by a seventh protein mass, protrusions of which are likely to be in contact with some of the outer subunits. A gamma subunit is supposed to be constituent part of this central protein mass. As a consequence, this model favours a stoichiometry of alpha 3 beta 3 gamma for the large subunits of beef heart F1-ATPase.
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PMID:An electron microscopic approach to the quaternary structure of mitochondrial F1-ATPase. 622 Aug 89

Rates of intramolecular electron transfer from a 1,1'-biphenylyl radical anion to six different acceptors on an androstane scaffold are examined with the aid of a theory that was developed recently to include effects of vibrational relaxations and dephasing. The electronic-interaction matrix element and other parameters needed for the theory are obtained by quantum-mechanical/molecular-mechanical simulations of the reactions in five solvents ranging from iso-octane to methyltetrahydrofuran. Intramolecular vibrational modes that are coupled to electron transfer are resolved in simulations in iso-octane and cyclohexane. The energies and coupling factors for these modes allow extension of the theory to incorporate transitions to and from excited vibrational levels. The calculated rates of electron transfer agree well with experimental measurements from the literature, except for reactions in which excited electronic states of the products become important.
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PMID:Effects of Free Energy and Solvent on Rates of Intramolecular Electron Transfer in Organic Radical Anions. 2886 84