N.m.r. study of the hydration of pyruvic acid

Griffiths, V. S.; Socrates, G.

doi:10.1039/tf9676300673

Cited by 25 publications

(11 citation statements)

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“…4b). Our results reproduce observations from literature indicating that ~40% of pyruvic acid (and/or pyruvate) are present in the hydrated form at pH = 2.5 47,48 . This pH is an estimated value for our sample at the moment of its zero-field NMR detection (see Methods).…”

Section: Resultssupporting

confidence: 91%

Zero-field nuclear magnetic resonance of chemically exchanging systems

et al. 2019

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Zero- to ultralow-field (ZULF) nuclear magnetic resonance (NMR) is an emerging tool for precision chemical analysis. In this work, we study dynamic processes and investigate the influence of chemical exchange on ZULF NMR J -spectra. We develop a computational approach that allows quantitative calculation of J -spectra in the presence of chemical exchange and apply it to study aqueous solutions of [ 15 N]ammonium ( 15 N ) as a model system. We show that pH-dependent chemical exchange substantially affects the J -spectra and, in some cases, can lead to degradation and complete disappearance of the spectral features. To demonstrate potential applications of ZULF NMR for chemistry and biomedicine, we show a ZULF NMR spectrum of [2- 13 C]pyruvic acid hyperpolarized via dissolution dynamic nuclear polarization (dDNP). We foresee applications of affordable and scalable ZULF NMR coupled with hyperpolarization to study chemical exchange phenomena in vivo and in situations where high-field NMR detection is not possible to implement.

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Section: Resultssupporting

confidence: 91%

Zero-field nuclear magnetic resonance of chemically exchanging systems

et al. 2019

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“…The well-preserved ratio of [1-13 C]pyruvate-hydrate to [1-13 C]pyruvate signal, obtained from individual time points in a single dynamic study as well as the areas under time courses of multiple dynamic studies, can reliably be used to scale the [1-13 C]pyruvate-hydrate signal to obtain a good estimation of the [1-13 C]pyruvate signal. Change in this ratio with pH has been previously reported (24), but we expect it to be negligible within the physiological range of pH. It has been assumed in this article that pyruvate hydrate and pyruvate are in rapid chemical equilibrium, which is partly supported by the good agreement between simulation and experimental results (Fig.…”

Section: Discussionsupporting

confidence: 82%

Robust hyperpolarized ¹³C metabolic imaging with selective non‐excitation of pyruvate (SNEP)

et al. 2015

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In vivo metabolic imaging using hyperpolarized [1-(13)C]pyruvate provides localized biochemical information and is particularly useful in detecting early disease changes, as well as monitoring disease progression and treatment response. However, a major limitation of hyperpolarized magnetization is its unrecoverable decay, due not only to T1 relaxation but also to radio-frequency (RF) excitation. RF excitation schemes used in metabolic imaging must therefore be able to utilize available hyperpolarized magnetization efficiently and robustly for the optimal detection of substrate and metabolite activities. In this work, a novel RF excitation scheme called selective non-excitation of pyruvate (SNEP) is presented. This excitation scheme involves the use of a spectral selective RF pulse to specifically exclude the excitation of [1-(13)C]pyruvate, while uniformly exciting the key metabolites of interest (namely [1-(13)C]lactate and [1-(13)C]alanine) and [1-(13)C]pyruvate-hydrate. By eliminating the loss of hyperpolarized [1-(13)C]pyruvate magnetization due to RF excitation, the signal from downstream metabolite pools is increased together with enhanced dynamic range. Simulation results, together with phantom measurements and in vivo experiments, demonstrated the improvement in signal-to-noise ratio (SNR) and the extension of the lifetime of the [1-(13)C]lactate and [1-(13)C]alanine pools when compared with conventional non-spectral selective (NS) excitation. SNEP has also been shown to perform comparably well with multi-band (MB) excitation, yet SNEP possesses distinct advantages, including ease of implementation, less stringent demands on gradient performance, increased robustness to frequency drifts and B0 inhomogeneity as well as easier quantification involving the use of [1-(13)C]pyruvate-hydrate as a proxy for the actual [1-(13)C] pyruvate signal. SNEP is therefore a promising alternative for robust hyperpolarized [1-(13)C]pyruvate metabolic imaging with high fidelity.

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“…The most favourable pH in the range 3-7 was 5 (reaction almost 4 faster than at pH 3), which could be rationalized by considering that the pK a of formic acid is 3.75 and that the formation of the formate adduct holds a central role in the catalytic transformation. 55,56 Lack of stability of pyruvate at low pH 82,83 could be affecting the efficiency of our catalysts in acidic solutions. Both an increase in the amount of formate and of temperature resulted in higher TON t and TOF values as anticipated.…”

Section: Catalytic Reduction Of Pyruvate To Lactatementioning

confidence: 99%