A simultaneous (15)N, (1)H- and (13)C, (1)H-HSQC with sensitivity enhancement and a heteronuclear gradient echo.

New pulse sequences are introduced and discussed that allow for simultaneous acquisition of (15)N,(1)H-and (13)C,(1)H-HSQC correlations for fully (13)C,(15)N-labeled biomacromolecules in combination with hetero-nuclear gradient echoes and sensitivity enhancement. The pulse sequence experimentally found to be optimal can be used as a building block, especially in time-consuming multidimensional NMR experiments. Due to the excellent solvent suppression obtained by employing heteronuclear gradient echoes, which allows detection of resonances under the water resonance, it would be possible to record two sensitivity-enhanced 4D experiments simultaneously on one sample dissolved in H(2)O, e.g. a 4D (13)C,(1)H-HSQC-NOESY-(15)N, (1)H/(13)C,(1)H-HSQC.