title: Angular dependence of dipole-dipole-Curie-spin cross-correlation effects in high-spin and low-spin paramagnetic myoglobin.
abstract: The (15)N-HSQC spectra of low-spin cyano-met-myoglobin and high-spin fluoro-met-myoglobin were assigned and dipole-dipole-Curie-spin cross-correlated relaxation rates measured. These cross-correlation rates originating from the dipolar (1)H-(15)N interaction and the dipolar interaction between the (1)H and the Curie spin of the paramagnetic center contain long-range angular information about the orientation of the (1)H-(15)N bond with respect to the iron-(1)H vector, with information measurable up to 11 A from the metal for the low-spin complex, and between 10 to 25 A for the high-spin complex. Comparison of the experimental data with predictions from crystal structure data showed that the anisotropy of the magnetic susceptibility tensor in low spin cyano-met-myoglobin significantly influences the cross-correlated dipole-dipole-Curie-spin relaxation rates.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institute, S-171 77 Stockholm, Sweden.
authors.forename: Guido
authors.initials: G
authors.lastname: Pintacuda
authors.forename: Karin
authors.initials: K
authors.lastname: Hohenthanner
authors.forename: Gottfried
authors.initials: G
authors.lastname: Otting
authors.forename: Norbert
authors.initials: N
authors.lastname: Müller
mesh_terms: D016880:Anisotropy; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009211:Myoglobin / Q000737:chemistry*; D009587:Nitrogen Isotopes
chemical_list: D009211:Myoglobin; D009587:Nitrogen Isotopes