Multiway decomposition of NMR spectra with coupled evolution periods.

Coupling evolution periods in NMR experiments on proteins has recently attracted much attention for its substantial savings in measurement time. Using the concept of multiway decomposition, which already proved useful in many types of NMR applications, the novel tool PRODECOMP decomposes sets of spectra with coupled evolution periods and attempts to provide all information that would be found in a corresponding full-dimensional spectrum. It offers the following advantages: (1) all experimental spectra are used simultaneously, avoiding sensitivity loss associated with individual examination of the spectra, (2) folding (aliasing) caused by the linear combinations of individual shifts in the projected spectra is automatically resolved, allowing for better resolution due to smaller spectral widths, (3) various types of schemes for the coupling of evolution periods are possible, (4) reconstructions of various high-dimensional spectra, including the corresponding full-dimensional spectrum, are straightforward, (5) overlap in both the projected and the directly detected dimensions is efficiently resolved. The capabilities of PRODECOMP are illustrated for a 14 kD protein, for which 12 projections of a five-dimensional spectrum with the nuclei N, HN, CO, Calpha, and Halpha are analyzed.