title: EPR signals of NADH: Q oxidoreductase. Shape and intensity.
abstract: (1) The EPR spectrum of Center 1 of NADH dehydrogenase in isolated Complex I or submitochondrial particles from beef heart consists of two overlapping nearly axial signals of the same intensity. They are defined as Center 1a (gll = 0.021, gl = 1.938) and Center 1b (gll = 2.021, gl = 1.928). (2) The line shape of the EPR spectrum of the Center 3+4 can be interpreted as an overlap of two rhombic signals of the same intensity. We define Center 3 by the g-values: gz=2.103, gy = 1.93-1.94, gx=1.884, and Center 4 by the values gz=2.04, gy=1.92-1.93, gx=1.863. (3) Direct quantitation of the individuals signals as well as computer stimulation suggests that the amount of the Centers 1a and 1b is only 25% of that of the other individuals centers and FMN. As EPR spectra of beef-heart submitochondrial particles at 10-20 K are nearly identical to those of Complex I, the same relative concentrations of the Fe-S centers are also present in the particles. (4) The signals either observed by us in EPR spectra of Complex I and submitochondrial particles at 4.2 K and high microwave powers can now be explained without assuming more than 5 paramagnetic centers in NADH dehydrogenase.
mesh_terms: D000818:Animals; D002417:Cattle; D004578:Electron Spin Resonance Spectroscopy; D008931:Mitochondria, Muscle / Q000201:enzymology; D009206:Myocardium; D009243:NAD; D009247:NADH, NADPH Oxidoreductases; D011485:Protein Binding; D011487:Protein Conformation; D014451:Ubiquinone
chemical_list: D009243:NAD; D014451:Ubiquinone; D009247:NADH, NADPH Oxidoreductases