Electron paramagnetic resonance properties of liver fluke ( Dicrocoelium dendriticum) nitrosyl hemoglobin

• Published in: FEBS letters 1984-01, Vol.166 (2), p.378-380
• Main Authors: Desideri, Alessandro, Meier, U.Thomas, Winterhalter, Kaspar H., Di Iorio, Ernesto E.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Dicrocoelium - metabolism; Dicrocoelium dendriticum; Distal histidine; Electron Spin Resonance Spectroscopy; ERP; Fundamental and applied biological sciences. Psychology; Hemoglobin; Hemoglobin, Trematoda; Hemoglobins - metabolism; Hydrogen-Ion Concentration; Kinetics; Liver fluke; Molecular biophysics; Spectroscopy : techniques and spectras
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(84)80116-7

The electron paramagnetic resonance properties of the nitric oxide derivative of liver fluke ( Dicrocoelium dendriticum) hemoglobin (DD-Hb) have been investigated in the pH range from 4.8 to 7.8. In the neutral and alkaline regions the spectra have a rhombic shape, with g x =2.09, g y =1.99 and g z =2.009, and a triplet hyperfine structure of 2.2 mT, due to the nitrogen of the bound NO molecule, in the center resonance. No superhyperfine lines in the g z region, related to the interaction of the iron with the proximal histidine, are detected, suggesting a large distance between the metal and the N ϵ of the imidazole. By lowering the pH the EPR spectrum undergoes a reversible change showing a 3-line pattern in the high-field region. Such a spectrum is fully formed at pH 4.8 and is interpreted in terms of a dissociation of the proximal histidine from the heme iron.