ABSTRACT
This chapter provides an outline of the two-dimensional nuclear magnetic resonance (2D NMR) methods that are most frequently used, for investigating protein structure in solution. The Fourier transform concept introduced into the NMR spectroscopy in 1966 by R. R. Ernst and W. A. Anderson inevitably transformed the NMR spectroscopy itself into a time-domain spectroscopy as opposed to the frequency-domain form practiced before. A completely different and general method for the investigation of nuclear Overhauser enhancement-s was proposed by J. Jeener et al.31 using the principles of 2D spectroscopy. A simple qualitative discussion of those 2D experiments which proved to be especially useful for the analysis of the H NMR spectra of polypeptides and small proteins. These include: 2D chemical shift correlation spectroscopy, 2D double-quantum spectroscopy, and 2D nuclear Overhauser enhancement spectroscopy. In fact, the components of the cross-peak multiplets have an absorption-mode lineshape in both dimensions in contrast to the diagonal peaks which are characterized by a dispersion-mode lineshape.
