Nuclear Overhauser effect spectroscopy combination experiments

In principle, 2D NMR structural determination of proteins in solution involves the linking of information derived from a combination of three complementary experiments - TOCSY (Total Correlated Spectroscopy), DQF-COSY (Double-Quantum Filtered Correlated Spectroscopy) and NOESY (Nuclear Overhauser Effect Spectroscopy). The TOCSY (58) spectra are used to identify spin systems of the amino acids in the protein. COSY (59,60) spectra yield complementary information to the TOCSY, which can be used to obtain the direct scalar connectives. The NOESY (61) spectra yield information on the through space relationship of protons in the protein. It should be noted that because of the vast abundance of hydrogen atoms in a protein molecule proton NMR is the preferred technique to determine the solution structure of a protein. 

All of the protons in each of 12 thermo- and photochromic BIPS were assigned through a combination of homonuclear decoupling experiments and correlation spectroscopy. The relative stereochemistry of the gem-dimethyl groups could be assigned on the basis of Nuclear Overhauser Effect (NOE) experiments.131... 

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