title: Sensitivity-enhanced detection of fast exchanging protons by an exchange-edited gradient HEHAHA-HSQC experiment.
abstract: An experiment is presented which allows for the sensitivity-enhanced measurement of proton exchange rates in a HSQC type experiment. Instead of using INEPT type transfer of magnetization from protons to heteronuclei and vice versa, we have used heteronuclear Hartmann-Hahn transfer, which is known to have higher sensitivity in the presence of chemical exchange. Direct NOE's between NH protons and alpha-protons are suppressed by an exchange-editing step unless the alpha-resonances are degenerate with the water resonance. A comparison between the exchange-edited HEHAHA-HSQC and a standard exchange-edited HSQC experiment performed on the uniformly 15N-labeled staphylococcal nuclease H124L shows an enhancement of approximately 100% with the former experiment. A set of one-dimensional exchange-edited spectra of urea was used for evaluating the ability to extract exchange rates using the presented experiment.
authors.affiliation: Department of Biochemistry, University of Minnesota, Medical School, 4-225 Millard Hall, 435 Delaware Street S.E., Minneapolis, Minnesota, 55455, USA.
authors.forename: K
authors.initials: K
authors.lastname: Zangger
authors.forename: I M
authors.initials: IM
authors.lastname: Armitage
mesh_terms: D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008961:Models, Structural; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014508:Urea / Q000737:chemistry*
chemical_list: D011522:Protons; D014508:Urea