Spectrospin Ag

Bruker Ag

Kurt Wuthrich

Richard R Ernst

Konstantin Pervushin

Gerhard Wider

Roland Riek

Slobodan Macura

A method for obtaining a nuclear magnetic resonance (NMR) correlation spectrum of heteronuclear spin systems, in particular comprising large molecules, especially biological macromolecules in solution, the spin system being subjected to a homogeneous magnetic field B.sub.0, being irradiated by a sequence of radio frequency (rf) pulses, is characterized in that the spin system comprises at least two kinds of spin 1/2 nuclei I and S being coupled to each other, whereby the sequence of rf pulses is chosen such that line broadening in the observed spectrum due to transverse relaxation (T.sub.2) is significantly reduced because of cross correlation between dipole--dipole (DD) coupling of the spins and chemical shift anisotropy (CSA), giving rise to different relaxation rates of the individual multiplet components of the spin system and chosen such that the relaxation effects of the two different mechanisms cancel each other out to a large degree. Thus, even very large biological macromolecules can be measured.

Transverse relaxation-optimized spectroscopy (=TROSY)

In recording two-dimensional nuclear magnetic resonance spectra, J cross peaks which hinder the interpretation of the spectragram and mask cross peaks of incoherent exchange processes or transfers are eliminated by one of two methods. In the first method, for each repetition of a measurement with an evolution period t.sub.1 between the first and second of two successive 90 degree pulses, the interval between the second and third 90 degree pulse (mixing time t.sub.m) is varied systematically in proportion to the evolution period. The two-dimensional spectra obtained is subjected to triangular multiplication or symmetrization so that all peaks which do not possess counterparts at the mirror symmetry positions of the main diagonal are eliminated. In the second method, the mixing time is kept constant and a 180 degree pulse is inserted between the second and third 90 degree pulse with a varying interval t.sub.p between the 180 degree pulse and the second 90 degree pulse for each repetition of a measurement. A spectrometer for carrying out this method permits critical parameters to be adjusted.

Method for recording two-dimensional nuclear magnetic resonance spectra

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Wallisellen, Switzerland

Kurt Wuthrich