Simultaneous α/β spin-state selection for ¹³C and ¹⁵N from a time-shared HSQC-IPAP experiment

Two novel HSQC-IPAP approaches are proposed to achieve α/β spin-state editing simultaneously for 13C and 15N in a single NMR experiment. The pulse schemes are based on a time-shared (TS) 2D 1H,13C/1H,15N-HSQC correlation experiment that combines concatenated echo elements for simultaneous J(CH) and J(NH) coupling constants evolution, TS evolution of 13C and 15N chemical shifts in the indirect dimension and heteronuclear α/β-spin-state selection by means of the IPAP principle. Heteronuclear α/β-editing for all CHn (n = 1-3) and NHn (1-2) multiplicities can be achieved in the detected F2 dimension of a single TS-HSQC-F2-IPAP experiment. On the other hand, an alternative TS-HSQC-F1-IPAP experiment is also proposed to achieve α/β-editing in the indirect F1 dimension. Experimental and simulated data is provided to evaluate these principles in terms of sensitivity and performance simultaneously on backbone and side-chain CH, CH2, CH3, NH, and NH2 spin systems in uniformly 13C/15N- labeled proteins and in small natural-abundance peptides. © Springer Science+Business Media B.V. 2006.