SELECTIVE DETECTION OF H-1-NMR RESONANCES OF (CHN)-C-13 GROUPS USING 2-DIMENSIONAL MAXIMUM-QUANTUM CORRELATION SPECTROSCOPY

Methods for editing spectra based upon maximum-quantum filtering in tw o-dimensional H-1 NMR are presented (MAXY NMR). Separation of H-1 reso nances from (CH)-C-13, (CH2)-C-13, and (CH3)-C-13 groups is demonstrat ed, using the coherence of the attached natural-abundance C-13 spin. T wo-dimensional correlation pulse sequences based on J connectivity (MA XY-COSY), total J connectivity (MAXY-TOCSY), and NOE and exchange proc esses (MAXY-NOESY) are given and exemplified using dexamethasone as a model compound. In addition, an improved form of a (CH2)-C-13-only COS Y spectrum (gem-COSY) is shown, and the application of z magnetic-fiel d gradients is demonstrated as an alternative to phase cycling. The ap proach should have utility in the assignment of complex H-1 NMR spectr a which arise from peptides or complex mixtures such as biofluids. (C) 1995 Academic Press, Inc.