title: Combination of DQ and ZQ coherences for sensitive through-bond NMR correlation experiments in biosolids under ultra-fast MAS.
abstract: A double-zero quantum (DZQ)-refocused INADEQUATE experiment is introduced for J-based NMR correlations under ultra-fast (60 kHz) magic angle spinning (MAS). The experiment records two spectra in the same dataset, a double quantum-single quantum (DQ-SQ) and zero quantum-single quantum (ZQ-SQ) spectrum, whereby the corresponding signals appear at different chemical shifts in ω(1). Furthermore, the spin-state selective excitation (S(3)E) J-decoupling block is incorporated in place of the second refocusing echo of the INADEQUATE scheme, providing an additional gain in sensitivity and resolution. The two sub-spectra acquired in this way can be treated separately by a shearing transformation, producing two diagonal-free single quantum (SQ-SQ)-type spectra, which are subsequently recombined to give an additional sensitivity enhancement, thus offering an improvement greater than a factor of two as compared to the original refocused INADEQUATE experiment. The combined DZQ scheme retains transverse magnetization on the initially polarized (I) spin, which typically exhibits a longer transverse dephasing time (T(2)') than its through-bond neighbour (S). By doing so, less magnetization is lost during the refocusing periods in the sequence to give even further gains in sensitivity for the J correlations. The experiment is demonstrated for the correlation between the carbonyl (CO) and alpha (CA) carbons in a microcrystalline sample of fully protonated, [(15)N,(13)C]-labelled Cu(II),Zn(II) superoxide dismutase, and its efficiency is discussed with respect to other J-based schemes.
authors.affiliation: Centre de RMN à Très Hauts Champs, UMR 5280 CNRS/Ecole Normale Supérieure de Lyon, University of Lyon, 5 rue de la Doua, 69100 Villeurbanne, France.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Webber
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pell
authors.forename: Emeline
authors.initials: E
authors.lastname: Barbet-Massin
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Knight
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
authors.forename: Isabella C
authors.initials: IC
authors.lastname: Felli
authors.forename: Roberta
authors.initials: R
authors.lastname: Pierattelli
authors.forename: Lyndon
authors.initials: L
authors.lastname: Emsley
authors.forename: Anne
authors.initials: A
authors.lastname: Lesage
authors.forename: Guido
authors.initials: G
authors.lastname: Pintacuda
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D003460:Crystallization; D006801:Humans; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D011789:Quantum Theory; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D013482:Superoxide Dismutase