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The metal sites of cytochrome oxidase
O,-UTILIZATION & PROCESSING 317 LIGNIN PEROXIDASE COMF'OUNDIII. M. H. Gold, H. Wariishi, K. Valli, M. Mylrajan, and T. M. Loehr, Oregon Graduate Center, Beaverton, OR 97006-1999, USA. Lignin peroxidase (Lip), an extracellularheme enzyme from the lignin-degrading fungus Phanerochaetechrysosporium,catalyzes the H,O,dependent oxidation of a variety of lignin model compounds with a pH optimum of 3.0. The H,O,-oxidized states and catalytic cycle of LiP are similar to HRP. At pH 3.0, in the absence of a reducing substrate and in the presence of excess H202, LiP is converted to LiP compound III (LiPIII) which is readily inactivated. Resonance Raman spectra of Lip111 indicate an Fe"*, low-spin species, suggesting an Fe1**02; complex. Addition of the _p.chrysosporiumsecondary metabolite veratryl alcohol (VA) results in the conversion of Lip111 to the native enzyme with the displacement of 02;. VA is not oxidized during this reaction.
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THE METAL SITES OF CYTOCHROME OXIDASE. G.N. George, S.P. Cramert, T.G. Frey* and R.C. Prince, Exxon Research and Engineering Co. Annandale, NJ 08801, t NSLS, BNL, Upton, NY 11973,
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* Dept. of Biology, San Diego State University, CA 92182, USA Polarized X-ray absorption and multifrequency epr spectroscopies have been used to probe the copper (CuA & CUB), iron (hemes a & ag) and zinc sites of bovine cytochrome oxidase in oriented membranous multilayers. The multifrequency epr reveals some aspects of the g=l2 signal associated with a less active form of the CUB-heme a3 site, and the orientation of the g-tensor of CuA with respect to the membrane. X-ray absorption spectroscopy reveals a tetragonal Cu (CUB), a long Cu-S/Cl bond (2.6A), and Fe-S/Cl ligation (2.3A). The long Cu-S/Cl and Fe-S/Cl bonds are oriented parallel and perpendicular to the membrane normal, respectively.
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CAKBONM~N~XDDE~INDIN~ ~0 T.THE~~~PHZLU~ ~YTOCHROME BA3ASPROBEDBYMOSSBAUERANDOPTKALSPECTROSCOPIES. MRusnak*,E.Mi_inck*, B. H. Zimmermannt, C.I. Nitschet, and J.A. Feet. *Gray Freshwater Biological Institute, Navarre, MN 55392, and bs Alamos National Laboratory, Los Alamos, NM 87545. Low temperature Mijssbauer spectroscopy of cytochrome ba3indicates that CO binds to cytochrome a3 to give a low-spin Fez+ spin state. After photolysis at TI 77 K, the iron attains a thermally stable high-spin Fe2+ configuration. The quadropole splitting and isomer shift of the photolyzed high-spin Fe 2+ CO-complex are distinct from those of the reduced enzyme, indicating that unliganded CO influences the electronic environment of the heme iron. Kinetic measurements by low-temperature optical spectroscopy yielded a value of 11.7 kcalmol-1 for the activation energy of CO rebinding, in accord with recent FTIR measurements (Einarsdottir et al., J. Biol. Chem, m, 2405-2408).
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THE METAL SITES OF CYTOCHROME OXIDASE. G.N. George, S.P. Cramert, T.G. Frey* and R.C. Prince, Exxon Research and Engineering Co. Annandale, NJ 08801, t NSLS, BNL, Upton, NY 11973,
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* Dept. of Biology, San Diego State University, CA 92182, USA Polarized X-ray absorption and multifrequency epr spectroscopies have been used to probe the copper (CuA & CUB), iron (hemes a & ag) and zinc sites of bovine cytochrome oxidase in oriented membranous multilayers. The multifrequency epr reveals some aspects of the g=l2 signal associated with a less active form of the CUB-heme a3 site, and the orientation of the g-tensor of CuA with respect to the membrane. X-ray absorption spectroscopy reveals a tetragonal Cu (CUB), a long Cu-S/Cl bond (2.6A), and Fe-S/Cl ligation (2.3A). The long Cu-S/Cl and Fe-S/Cl bonds are oriented parallel and perpendicular to the membrane normal, respectively.
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CAKBONM~N~XDDE~INDIN~ ~0 T.THE~~~PHZLU~ ~YTOCHROME BA3ASPROBEDBYMOSSBAUERANDOPTKALSPECTROSCOPIES. MRusnak*,E.Mi_inck*, B. H. Zimmermannt, C.I. Nitschet, and J.A. Feet. *Gray Freshwater Biological Institute, Navarre, MN 55392, and bs Alamos National Laboratory, Los Alamos, NM 87545. Low temperature Mijssbauer spectroscopy of cytochrome ba3indicates that CO binds to cytochrome a3 to give a low-spin Fez+ spin state. After photolysis at TI 77 K, the iron attains a thermally stable high-spin Fe2+ configuration. The quadropole splitting and isomer shift of the photolyzed high-spin Fe 2+ CO-complex are distinct from those of the reduced enzyme, indicating that unliganded CO influences the electronic environment of the heme iron. Kinetic measurements by low-temperature optical spectroscopy yielded a value of 11.7 kcalmol-1 for the activation energy of CO rebinding, in accord with recent FTIR measurements (Einarsdottir et al., J. Biol. Chem, m, 2405-2408).