Simultaneous measurement of N-H and Calpha-Halpha coupling constants in proteins.
We present a pulse sequence for the simultaneous measurement of N-H and Calpha-Halpha couplings in double-labeled proteins from 2D spectra. The proposed sequence, a modification of the HN(CO)CA experiment, combines the J-modulation method and the IPAP scheme. The couplings can be readily retrieved from a series of 2D (15)N-(1)H correlation spectra, differing in the time point at which a (1)H 180 degrees pulse is applied. This induces an intensity modulation of the (15)N-(1)H correlation peaks with the Calpha-Halpha coupling. The Calpha-Halpha coupling is then obtained by fitting the observed intensities to the modulation equation. The N-H coupling is measured in each member of the set from peak-to-peak separations in the IPAP subspectra. The pulse sequence is experimentally verified with a sample of (15)N/(13)C-enriched ubiquitin.
Instituto de Química Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
David
D
Pantoja-Uceda
Jorge
J
Santoro
D002244:Carbon / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009584:Nitrogen / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D025801:Ubiquitin / Q000737:chemistry
D011506:Proteins; D025801:Ubiquitin; D002244:Carbon; D006859:Hydrogen; D009584:Nitrogen