title: Hydrogen bonding affects the [NiFe] active site of Desulfovibrio vulgaris Miyazaki F hydrogenase: a hyperfine sublevel correlation spectroscopy and density functional theory study.
abstract: Pulse electron paramagnetic resonance and hyperfine sublevel correlation spectroscopy have been used to investigate nitrogen coordination of the active site of [NiFe] hydrogenase of Desulfovibrio vulgaris Miyazaki F in its oxidized "ready" state. The obtained (14)N hyperfine (A = [+1.32, +1.32, +2.07] MHz) and nuclear quadrupole (e(2)qQ/h = -1.9 MHz, eta = 0.37) coupling constants were assigned to the N(epsilon) of a highly conserved histidine (His88) by studying a hydrogenase preparation in which the histidines were (15)N labeled. The histidine is hydrogen-bonded via its N(epsilon)-H to the nickel-coordinating sulfur of a cysteine (Cys549) that carries an appreciable amount of spin density. Through the hydrogen bond a small fraction of the spin density ( approximately 1%) is delocalized onto the histidine ring giving rise to an isotropic (14)N hyperfine coupling constant of about 1.6 MHz. These conclusions are supported by density functional calculations. The measured (14)N quadrupole coupling constants are related to the polarization of the N(epsilon)-H bond, and the respective hydrogen bond can be classified as being weak.
authors.affiliation: Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Aruna Goenka
authors.initials: AG
authors.lastname: Agrawal
authors.forename: Maurice
authors.initials: M
authors.lastname: van Gastel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Gärtner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lubitz
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003545:Cysteine / Q000737:chemistry; D016969:Desulfovibrio vulgaris / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D006864:Hydrogenase / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D006639:Histidine; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D003545:Cysteine