title: Quantitative measurement of small through-hydrogen-bond and 'through-space' 1H-113Cd and 1H-199Hg J couplings in metal-substituted rubredoxin from Pyrococcus furiosus.
abstract: A method is described for measurement of small unresolvable heteronuclear J couplings. The method is based on quantitative analysis of a phase-purged heteronuclear spin-echo difference spectrum, and is demonstrated for measuring 1H-113Cd and 1H-199Hg J couplings in metal-substituted rubredoxin (M(r) approximately 5.4 kDa) from Pyrococcus furiosus. Couplings from cadmium to backbone amide protons that are hydrogen bonded to the Cys-S atoms directly bonded to Cd vary from smaller than 0.3 to 1.8 Hz; a 'through-space' coupling between Cd and the protons of an alanine methyl group was measured to be 0.3 Hz. Couplings to 199Hg are significantly larger and fall in the 0.4-4 Hz range.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland Baltimore County 21228.
authors.forename: P R
authors.initials: PR
authors.lastname: Blake
authors.forename: B
authors.initials: B
authors.lastname: Lee
authors.forename: M F
authors.initials: MF
authors.lastname: Summers
authors.forename: M W
authors.initials: MW
authors.lastname: Adams
authors.forename: J B
authors.initials: JB
authors.lastname: Park
authors.forename: Z H
authors.initials: ZH
authors.lastname: Zhou
authors.forename: A
authors.initials: A
authors.lastname: Bax
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000737:chemistry*; D002104:Cadmium / Q000737:chemistry*; D006860:Hydrogen Bonding; D008628:Mercury / Q000737:chemistry*; D011487:Protein Conformation; D012416:Rubredoxins / Q000737:chemistry*
chemical_list: D012416:Rubredoxins; D002104:Cadmium; D008628:Mercury