JOURNAL OF MAGNETIC RESONANCE t&393-399 ( 1989) COMMUNICATIONS R&i Recording of 2D NMR Spectra Appkatk~~ ~ to the Study of Hydmgen E

Although the inherent sensitivity of ID and 2D NMR spectroscopy is not very different ( 1) , the minimum time needed for recording a 2D NMR spectrum is typi-cally many orders of magnitude longer. This stems from the requirement to sample a sufficiently large number oft I increments, necessary to obtain adequate digital reso-lution in the I;, dimension of the final spectrum. Moreover, the pulse sequence is usually repeated many times for each t, value, with different phases of the RF pulses, in a process referred to as phase cycling. This phase cycling is used to eliminate spuri-ous resonances such as axial peaks and quadrature artifacts from the 2D spectrum, or to select desired coherence transfer pathways. Here we demonstrate that high quality 2D NMR spectra can be recorded very rapidly, without using phase cycling. This can result in dramatic time savings for commonly used sensitive ‘H experiments such as COSY, HQI-IAHA (2, 3), or HMQC (4-6) and makes it possible to study, on a relatively rapid time scale, ‘H exchange phenomena in proteins with spectra too complex for analysis by 1 D NMR. In the absence of phase cycling, it is important to minimize the inherent source