G-matrix Fourier transformation (GFT) nuclear magnetic resonance (NMR) experiments for resonance assignment and structure determination of organic molecules

A method of conducting a (5,3) dimensional (D) [HN{N,CO}{CαβCα}] G-matrix Fourier transformation (GFT) nuclear magnetic resonance (NMR) experiment, said method comprising:

• providing a sample, wherein said sample is a protein molecule having two consecutive amino acid residues, i−1 and i, and the chemical shift values for the following nuclei are measured:
• (1) α- and β-carbons of amino acid residues i and i−1, 13Cα/βi/i−1;
• (2) a polypeptide backbone amide nitrogen of amino acid residue i, 15Ni;
• (3) a polypeptide backbone carbonyl carbon of amino acid residue i−1, 13C′i−1;
• and (4) a polypeptide backbone amide proton of amino acid residue i, 1HNi;
• applying radiofrequency pulses for a first 5D FT NMR experiment to the sample;
• using a spectrometer;
• selecting a first set of 2 indirect chemical shift evolution periods of the 5D FT NMR experiment, 13Cα/βi/i−1 and 13Cαi/i−1;
• jointly sampling the first set of 2 indirect chemical shift evolution periods in a first indirect time domain dimension, t1(13Cα/βi/i−1, 13Cαi/i−1), whereby chemical shift evolution periods which provide sequential connectivities and spectral resolution are subjected to the joint sampling in the first indirect time dimension;
• selecting a second set of 2 indirect chemical shift evolution periods of the 5D FT NMR experiment, 15Ni and 13C′i−1;
• jointly sampling the second set of 2 indirect chemical shift evolution periods in a second indirect time domain dimension, t2(15Ni, 13C′i−1), whereby chemical shift evolution periods which serve to provide spectral resolution are subjected to separate joint sampling in the second indirect time dimension;
• independently cosine and sine modulating NMR signals detected in a direct dimension to generate 3D basic NMR spectra comprising frequency domain signals having a chemical shift multiplet with 4 components resulting from each of 2 chemical shift doublet components in a first frequency domain dimension, ω1(13Cα/β, 13Cα), giving rise to 2 chemical shift doublet components in a second frequency domain dimension, ω2(15N, 13C′), thereby enabling phase-sensitive sampling of all 4 indirect chemical shift evolution periods;
• and
• transforming the 3D basic NMR spectra into 3D phase-sensitively edited basic NMR spectra, wherein the 4 chemical shift multiplet components of the 3D basic NMR spectra are edited to yield 3D phase-sensitively edited basic NMR spectra having individual chemical shift multiplet components.