(19)F Paramagnetic Relaxation Enhancement: A Valuable Tool for Distance Measurements in Proteins.
Fluorine NMR paramagnetic relaxation enhancement was evaluated as a versatile approach for extracting distance information in selectively F-labeled proteins. Proof of concept and initial applications are presented for the HIV-inactivating lectin cyanovirin-N. Single F atoms were introduced at the 4-, 5-, 6- or 7 positions of Trp49 and the 4-position of Phe4, Phe54, and Phe80. The paramagnetic nitroxide spin label was attached to Cys residues that were placed into the protein at positions 50 or 52. (19)F-T2  NMR spectra with different relaxation delays were recorded and the transverse (19)F-PRE rate, (19)F-Γ2 , was used to determine the average distance between the F nucleus and the paramagnetic center. Our data show that experimental (19)F PRE-based distances correspond to 0.93 of the (1)HN-PRE distances, in perfect agreement with the gyromagnetic γ(19)F/γ(1)H ratio, thereby demonstrating that (19)F PREs are excellent alternative parameters for quantitative distance measurements in selectively F-labeled proteins.
Department of Structural Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15260 (USA).
Elena
E
Matei
Department of Structural Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15260 (USA). amg100@pitt.edu.
Angela M
AM
Gronenborn
D005461:Fluorine; D019906:Nuclear Magnetic Resonance, Biomolecular; D011506:Proteins / Q000737:chemistry*
D011506:Proteins; D005461:Fluorine
NMR spectroscopy; distances; fluorine; paramagnetic relaxation enhancements; proteins