title: 2H[19F] REDOR for distance measurements in biological solids using a double resonance spectrometer.
abstract: A new approach for distance measurements in biological solids employing 2H[19F] rotational echo double resonance was developed and validated on 2H,19F-D-alanine and an imidazopyridine based inhibitor of the gastric H+/K+-ATPase. The 2H-19F double resonance experiments presented here were performed without 1H decoupling using a double resonance NMR spectrometer. In this way, it was possible to benefit from the relatively longer distance range of fluorine without the need of specialized fluorine equipment. A distance of 2.5 +/- 0.3 A was measured in the alanine derivative, indicating a gauche conformation of the two labels. In the case of the imidazopyridine compound a lower distance limit of 5.2 A was determined and is in agreement with an extended conformation of the inhibitor. Several REDOR variants were compared, and their advantages and limitations discussed. Composite fluorine dephasing pulses were found to enhance the frequency bandwidth significantly, and to reduce the dependence of the performance of the experiment on the exact choice of the transmitter frequency.
authors.affiliation: Biomembrane Structure Unit, Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK.
authors.forename: Stephan L
authors.initials: SL
authors.lastname: Grage
authors.forename: Jude A
authors.initials: JA
authors.lastname: Watts
authors.forename: Anthony
authors.initials: A
authors.lastname: Watts
mesh_terms: D000409:Alanine / Q000737:chemistry*; D003461:Crystallography / Q000379:methods*; D003903:Deuterium; D005240:Feasibility Studies; D005462:Fluorine Radioisotopes; D017506:H(+)-K(+)-Exchanging ATPase / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011487:Protein Conformation; D054328:Proton Pump Inhibitors; D011725:Pyridines / Q000737:chemistry*; D013113:Spin Labels; D013270:Stomach / Q000737:chemistry
chemical_list: D005462:Fluorine Radioisotopes; D054328:Proton Pump Inhibitors; D011725:Pyridines; D013113:Spin Labels; D003903:Deuterium; D017506:H(+)-K(+)-Exchanging ATPase; D000409:Alanine