title: Temperature dependence of the electron spin-lattice relaxation rate from pulsed EPR of CUA and heme a in cytochrome c oxidase.
abstract: This work shows the feasibility of using pulsed, saturation recovery EPR to study directly the magnetic relaxation properties of metal centers in cytochrome c oxidase in the 1.5-20 K range. Heme a and CuA both showed remarkably similar Tn temperature dependences in their spin-lattice relaxation rates. Either both are in environments with very similar protein backbone configurations (Stapleton, H.J., J.P. Allen, C.P. Flynn, D.G. Stinson, and S.R. Kurtz, 1980, Phys. Rev. Lett., 45:1456-1459; Allen, J.P., J.T. Colvin, D.G. Stinson, C.P. Flynn, and H.J. Stapleton, 1982, Biophys. J., 38:299-310), or the CuA is relaxed by nearby heme a. Spin-lattice relaxation of the nitrosylferrocytochrome a3 center in mixed valence oxidase showed enhancement of relaxation by a nearby paramagnetic center, most likely heme a.
mesh_terms: D000818:Animals; D002417:Cattle; D003300:Copper; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV; D006418:Heme; D013816:Thermodynamics
chemical_list: D006418:Heme; D003300:Copper; D003576:Electron Transport Complex IV