SOFAST-HMQC experiments for recording two-dimensional heteronuclear correlation spectra of proteins within a few seconds

Fast multidimensional NMR with a time resolution of a few seconds provides a new tool for high throughput screening and site-resolved real-time studies of kinetic molecular processes by NMR. Recently we have demonstrated the feasibility to record protein H-1-N-15 correlation spectra in a few seconds of acquisition time using a new SOFAST-HMQC experiment (Schanda and Brutscher (2005) J. Am. Chem. Soc. 127, 8014). Here, we investigate in detail the performance of SOFAST-HMQC to record H-1-N-15 and H-1-C-13 correlation spectra of proteins of different size and at different magnetic field strengths. Compared to standard H-1-N-15 correlation experiments SOFAST-HMQC provides a significant gain in sensitivity, especially for fast repetition rates. Guidelines are provided on how to set up SOFAST-HMQC experiments for a given protein sample. In addition, an alternative pulse scheme, IPAP-SOFAST-HMQC is presented that allows application on NMR spectrometers equipped with cryogenic probes, and fast measurement of one-bond H-1-C-13 and H-1-N-15 scalar and residual dipolar coupling constants.