Recovery of underwater resonances by magnetization transferred NMR spectroscopy (RECUR-NMR)

A method for detecting small molecule NMR resonances under a water peak in biological samples is presented. After high-efficiency solvent suppression using double WATERGATE, either a TOCSY- or ROESY-based coherence transfer s equence is applied to reestablish the resonances close to, or under, water through magnetization transfer using scalar or dipolar coupling, respective ly. The use of the TOCSY and ROESY methods ensures an in-phase magnetizatio n transfer, which makes the new approach readily extended for the measureme nt of transverse relaxation times, internuclear ROEs, and ROE buildup rates . An extension of the new approach for J-resolved spectroscopy is also pres ented and tested using a sample of human blood plasma. (C) 2001 Academic Pr ess.