Protein folding studied by real-time NMR spectroscopy.

Real-time NMR spectroscopy developed to a generally applicable method to follow protein folding reactions. It combines the access to high resolution data with kinetic experiments allowing very detailed insights into the development of the protein structure during different steps of folding. The present review concentrates mainly on the progress of real-time NMR during the last 5 years. Starting from simple 1D experiments, mainly changes of the chemical shifts and line widths of the resonances have been used to analyze the different states populated during the folding reactions. Today, we have a broad spectrum of 1D, 2D, and even 3D NMR methods focusing on different characteristics of the folding polypeptide chains. More than 20 proteins have been investigated so far by these time-resolved experiments and the main results and conclusions are discussed in this report. Real-time NMR provides comprehensive contributions for joining experiment and theory within the 'new view' of protein folding.