Doros T. Petasis

Learn More
The effects of NO and fluoride on the iron-quinone complex of the acceptor side of Photosystem II (PSII) are examined by Xand Q-band EPR spectroscopy. It is found that the EPR signal of the ironnitrosyl complex changes upon addition of F-. The change is determined to be due to a superhyperfine interaction between the electronic spin (S ) /2) and the(More)
The tetraheme cytochrome c(554) (cyt c(554)) from Nitrosomonas europaea is an essential electron transfer component in the biological oxidation of ammonia. The protein contains one 5-coordinate heme and three bis-His coordinated hemes in a 3D arrangement common to a newly characterized class of multiheme proteins. The ligand binding, electrochemical(More)
Hydroxylamine oxidoreductase (HAO) from the autotrophic nitrifying bacterium Nitrosomonas europaea catalyzes the oxidation of NH(2)OH to HNO(2). The enzyme contains eight hemes per subunit which participate in catalytic function and electron transport. The structure of the enzyme shows a unique spatial arrangement of the eight hemes, subsets of which are(More)
We report the results of studies of a series of water-soluble peptide adducts of iron mesoporphyrin IX (FeMPIX). In one group of compounds, the peptide-sandwiched mesohemes (PSMs; 1-5), two identical 13-residue peptides are connected to the propionate groups of FeMPIX via amide linkages with N nitrogens of lysine (Lys) residues. The corresponding(More)
The reaction of m-terphenyl-based carboxylic acids with ferrous salts produces novel tetracarboxylate dinuclear clusters through an extraordinarily efficient self-assembly process. Recently, we reported the preparation of one such compound, [Fe2(μ-O2CAr)2(O2CAr)2(C5H5N)2] (1), and highlighted its unique reactivity with dioxygen.1 Efforts to explore this(More)
Existing Q-band (35 GHz) EPR spectrometers employ cylindrical cavities for more intense microwave magnetic fields B1, but are so constructed that only one orientation between the external field B and B1 is allowed, namely the B perpendicular B1 orientation, thus limiting the use of the spectrometer to measurements on Kramers spin systems (odd electron(More)
Electron paramagnetic resonance (EPR) spectroscopy has long been a primary method for characterization of paramagnetic centers in materials and biological complexes. Transition metals in biological complexes have valence d-orbitals that largely define the chemistry of the metal centers. EPR spectra are distinctive for metal type, oxidation state, protein(More)
  • 1