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13C−13C NOESY:  An Attractive Alternative for Studying Large Macromolecules

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journal contribution
posted on 21.01.2004, 00:00 by Ivano Bertini, Isabella C. Felli, Rainer Kümmerle, Detlef Moskau, Roberta Pierattelli
13C direct detection provides a valuable alternative to 1H detection to overcome fast relaxation because of its smaller magnetic moment. 13C−13C NOESY spectra were acquired for a dimeric protein of molecular mass 32 000 and for a monomeric analogue. With increasing molecular mass, the quality of 13C−13C NOESY spectra improves while the scalar-based experiments become less sensitive, as predicted by the increase in the molecular mass. 13C−13C NOESY spectra of the dimer were acquired with different mixing times. The mixing time can be tuned to detect mainly one-bond correlations, or it can be increased to also detect correlations between nuclei at longer distances. It is proposed that 13C−13C dipolar-based experiments provide a promising tool for signal detection and assignment in large macromolecules, such as multimeric species and macromolecular complexes, for which scalar-based experiments become less effective.