Optimum spin-state selection for all multiplicities in the acquisition dimension of the HSQC experiment.
Most conventional heteronuclear spin-state-selective (S(3)) NMR experiments only work for a specific multiplicity, typically IS spin systems. Here, we introduce a general and efficient IPAP strategy to achieve S(3) editing simultaneously for all multiplicities in the acquisition dimension of the HSQC experiment. Complementary in-phase (HSQC-IP) and anti-phase (HSQC-AP) data are separately recorded with a simple phase exchange of two 90 degrees proton pulses involved in the mixing process of the F2-coupled sensitivity-improved HSQC pulse sequence. Additive and subtractive linear combination of these IP/AP data generates simplified F2-alpha/beta-spin-edited HSQC subspectra for all IS, I(2)S, and I(3)S spin systems and combines enhanced and optimized sensitivity with excellent tolerance to unwanted cross-talk contributions over a considerable range of coupling constants. Practical aspects such as pulse phase settings, transfer efficiency dependence, inter-pulse delay optimization, and percentage of cross-talk are theoretically analyzed and discussed as a function of each I(n)S multiplicity. Particular emphasis on the features associated to spin-editing in diastereotopic I(2)S spin systems and application to the measurement of long-range proton-carbon coupling constants are also provided.
Nolis
Pau
P
Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Spain.
Espinosa
Juan Félix
JF
Parella
Teodor
T
D002247:Carbon Isotopes; D003198:Computer Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D012680:Sensitivity and Specificity; D025801:Ubiquitin / Q000737:chemistry*
D002247:Carbon Isotopes; D025801:Ubiquitin