Determination of scalar coupling constants by inverse Fourier transformation of in-phase multiplets

Abstract

A generally applicable new method for the determination of scalar coupling constants for spins with a single coupling partner, in particular 3JHNα. in polypeptides, is described. It has the special advantage for use in protein structure determinations that no extra NMR experiments need to be recorded, and that NOE distance constraints and dihedral angle constraints from 3JHNα can be derived from the same data sets. The scalar coupling constants are extracted from the in-phase multiplets of homonuclear [1H, 1H] NOESY spectra or heteronuclear [15N, 1H ] COSY spectra through inverse Fourier transformation of the data points representing a cross peak along ω2, and a subsequent nonlinear least-squares fit in the time domain. Practical applications are described for recombinant hirudin and the basic pancreatic trypsin inhibitor. Show more