Electron paramagnetic resonance studies of the soluble CuA protein from the cytochrome ba3 of Thermus thermophilus.
AUTOR(ES)
Karpefors, M
RESUMO
The electron paramagnetic resonance (EPR) spectrum of the binuclear CuA center in the water-soluble subunit II fragment from cytochrome ba3 of Thermus thermophilus was recorded at 3.93, 9.45, and 34.03 GHz, and the EPR parameters were determined by computer simulations. The frequency and M1 dependence of the linewidth was discussed in terms of g strain superimposed on a correlation between the A and g values. The g values were found to be gx = 1.996, gy = 2.011, gz = 2.187, and the two Cu ions contribute nearly equally to the hyperfine structure, with magnitude of Ax magnitude of approximately 15 G, magnitude of Ay magnitude = 29 G, and magnitude of Az magnitude of = 28.5 G (65Cu). Theoretical CNDO/S calculations, based on the x-ray structure of the Paracoccus denitrificans enzyme, yield a singly occupied antibonding orbital in which each Cu is pi*-bonded to one S and sigma*-bonded to the other. In contrast to the equal spin distribution suggested by the EPR simulations, the calculated contributions from the Cu ions differ by a factor of 2. However, only small changes in the ligand geometry are needed to reproduce the experimental results.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1233768Documentos Relacionados
- Properties of a copper-containing cytochrome ba3: a second terminal oxidase from the extreme thermophile Thermus thermophilus.
- Reaction of cyanide with cytochrome ba3 from Thermus thermophilus: spectroscopic characterization of the Fe(II)a3-CN.Cu(II)B-CN complex suggests four 14N atoms are coordinated to CuB.
- Proton magnetic resonance spectra of tRNA-Met-f from Thermus thermophilus.
- Structure and mechanism of the aberrant ba3-cytochrome c oxidase from Thermus thermophilus
- Crystal structure of the ribosomal protein S6 from Thermus thermophilus.