Maximum likelihood constrained deconvolution. II: Application to experimental two‐ and three‐dimensional NMR spectra

Abstract

AbstractThe maximum likelihood method (MLM) and related protocols were applied to the experimental 2‐D nuclear Overhauser effect (NOE) spectrum of a 24‐nucleotide RNA hairpin loop molecule. The output becomes more valuable when diagonal symmeterization is followed by MLM. This symmeterized maximum likelihood (SML) protocol restores the original spectral information with high fidelity by accurately partitioning components from overlapped peaks and provides substantial improvements in line shape and spectral resolution, in particular in the F1 dimension. These advantages lead to a simpler interpretation of the resonance frequencies, intensities, multiplet fine structure, and J‐coupling values from a heavily overlapped peak region. This promises a more effective tool for peak picking, assignment, and integration. Also, application of MLM and related protocols to the 2‐D NOE proton spectrum of a 24‐mer RNA dramatically increases the number of NOE‐based distance constraints that can be used for determination of its 3‐D molecular structure. By application of 3‐D MLM to a simple 3‐D spectrum, the spectral resolution and signal‐to‐noise (S/N) ratio was greatly improved by effective line sharpening and reduction of cross‐talk between planes. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson 18A: 146–156, 2003