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Singlet-filtered NMR spectroscopy

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Science Advances  21 Feb 2020:
Vol. 6, no. 8, eaaz1955
DOI: 10.1126/sciadv.aaz1955
  • Fig. 1 A robust and versatile singlet NMR sequence.

    The gc-M2S pulse sequence for converting longitudinal magnetization into singlet spin order and back to magnetization in a homonuclear 2 spin-½ system is shown. Full and empty rectangles represent π/2 and π hard pulses, respectively, and the semicircles represent gradients. The sequence consists of a magnetization-to-singlet block, a T00 block to project into the singlet state, a singlet-to-magnetization block, a z-purge block, and a (π/2)ϕ5 observe block. The phases ϕ1 and ϕ4 are collinear. The phases ϕ2 and ϕ3 are collinear but in quadrature to ϕ1 and ϕ4. The relevant product operators of each step are given on the right. The detailed discussion can be found in the Supplementary Materials.

  • Fig. 2 Filtering signals in Aβ.

    1H NMR spectroscopy of glycine residues in Aβ40 at 278 K in a 16.48-T (700-MHz) magnet. (A) From top to bottom: Amino acid sequence and 1D-NMR 1H (in black) and singlet-filtered spectra (in colors) for a 95 μM Aβ40 in D2O. (B) Two-dimensional NMR 1H-1H correlation spectroscopy for a 95 μM Aβ40 in (90%/10%) H2O/D2O: TOCSY (60 ms mixing time, gray contours) with overlaid singlet-filtered TOCSYs (45 ms mixing time) using sequence parameters selective for G29 (purple contour), G33 (green contours), G37 (blue contours), and G38 (red contours), respectively. Full spectra are presented in the Supplementary Materials.

  • Fig. 3 Analyzing metabolites in the brain via singlet states.

    (A) Top to bottom: the 1H NMR spectrum of ex vivo mouse brains (128 scans, spectrum is divided by 32) and the corresponding singlet-filtered NAAβ and Glxγ spectra (128 scans, acquisition time ~3 min). In all the spectra, a polynomial pulse sequence was appended for water suppression. All experiments have been conducted at 7.05 T (300 MHz). The experimental parameters for the sequence are reported in table S4. The composition of the buffer is reported in the Supplementary Materials. (B) T1 of the Glx signal and (C) TS, displaying long-lived behavior.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/8/eaaz1955/DC1

    Supplementary information

    Fig. S1. The plot represents the M2SSQ transfer function fSQM2S(n¯1)=|Sinn¯1θ1|, where n¯1(ε) is given in Eq. 4.

    Fig. S2. Dependence of e of the sequence parameters and transfer function.

    Fig. S3. The numerical simulation illustrates the spin dynamics during the core magnetization-to-singlet and singlet-to-magnetization blocks.

    Fig. S4. NMR spectra and singlet filtering of model compounds at various magnetic fields.

    Fig. S5. The influence of the offset on the NMR signal passing through the gc-M2S sequence was evaluated in experiments on AGG at 21.15 T (900 MHz).

    Fig. S6. 1H NMR spectrum of Aβ40 in D2O at 16.48 T (~700 MHz) and 278 K using a polynomial sequence for water suppression.

    Fig. S7. 1H NMR singlet-filtered spectra of Aβ40 in D2O at 16.48 T (~700 MHz) and 278 K using the sequence of Fig. 1 with the parameters reported in table S3 to achieve selectivity for each glycine residue.

    Fig. S8. 1H NMR singlet-filtered spectra of Aβ40 in H2O/D2O (90%/10%) at 16.48 T (~700 MHz) and 278 K using the sequence of Fig. 1 with the parameters reported in table S3 to achieve selectivity for each glycine residue.

    Fig. S9. TOCSY spectrum of Aβ40 in H2O/D2O (90%/10%) 16.48 T (~700 MHz) and 278 K obtained using a 60-ms DIPSI2 (ωRF = 10 kHz) mixing block.

    Fig. S10. Singlet-filtered TOCSYs spectra of Aβ40 in H2O/D2O (90%/10%) at 16.48 T (~700 MHz) and 278 K obtained using a 45-ms DIPSI2 (ωRF = 10 kHz) mixing block.

    Fig. S11. Tissue control experiments.

    Table S1. The table reports the constants defining the nuclear spin Hamiltonian as well as the parameters used to set the GE-M2S sequence in the experiments on the H2N-AlanylGlycilGlycine-OH (AGG) peptide presented in figs. S4 (B to D) and S5.

    Table S2. The table reports the constants defining the nuclear spin Hamiltonian as well as the parameters used to set the gc-M2S sequence in the experiments on 2,3-dibromotiophene presented in fig. S4 (F to H).

    Table S3. The table reports the constants defining the nuclear spin Hamiltonian as well as the parameters used to set the gc-M2S sequence in the experiments on Aβ40 presented in Fig. 2B.

    Table S4. The table reports parameters used to set the gc-M2S sequence in the experiments on mouse brains presented in Fig. 3.

    Materials and methods extended

    References (41, 42)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary information
    • Fig. S1. The plot represents the M2SSQ transfer function fSQM2S(n¯1)=|Sinn¯1θ1|, where n¯1(ε) is given in Eq. 4.
    • Fig. S2. Dependence of ε of the sequence parameters and transfer function.
    • Fig. S3. The numerical simulation illustrates the spin dynamics during the core magnetization-to-singlet and singlet-to-magnetization blocks.
    • Fig. S4. NMR spectra and singlet filtering of model compounds at various magnetic fields.
    • Fig. S5. The influence of the offset on the NMR signal passing through the gc-M2S sequence was evaluated in experiments on AGG at 21.15 T (900 MHz).
    • Fig. S6. 1H NMR spectrum of Aβ40 in D2O at 16.48 T (~700 MHz) and 278 K using a polynomial sequence for water suppression.
    • Fig. S7. 1H NMR singlet-filtered spectra of Aβ40 in D2O at 16.48 T (~700 MHz) and 278 K using the sequence of Fig. 1 with the parameters reported in table S3 to achieve selectivity for each glycine residue.
    • Fig. S8. 1H NMR singlet-filtered spectra of Aβ40 in H2O/D2O (90%/10%) at 16.48 T (~700 MHz) and 278 K using the sequence of Fig. 1 with the parameters reported in table S3 to achieve selectivity for each glycine residue.
    • Fig. S9. TOCSY spectrum of Aβ40 in H2O/D2O (90%/10%) 16.48 T (~700 MHz) and 278 K obtained using a 60-ms DIPSI2 (ωRF = 10 kHz) mixing block.
    • Fig. S10. Singlet-filtered TOCSYs spectra of Aβ40 in H2O/D2O (90%/10%) at 16.48 T (~700 MHz) and 278 K obtained using a 45-ms DIPSI2 (ωRF = 10 kHz) mixing block.
    • Fig. S11. Tissue control experiments.
    • Table S1. The table reports the constants defining the nuclear spin Hamiltonian as well as the parameters used to set the GE-M2S sequence in the experiments on the H2N-AlanylGlycilGlycine-OH (AGG) peptide presented in figs. S4 (B to D) and S5.
    • Table S2. The table reports the constants defining the nuclear spin Hamiltonian as well as the parameters used to set the gc-M2S sequence in the experiments on 2,3-dibromotiophene presented in fig. S4 (F to H).
    • Table S3. The table reports the constants defining the nuclear spin Hamiltonian as well as the parameters used to set the gc-M2S sequence in the experiments on Aβ40 presented in Fig. 2B.
    • Table S4. The table reports parameters used to set the gc-M2S sequence in the experiments on mouse brains presented in Fig. 3.
    • Materials and methods extended
    • References (41, 42)

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