Andrey N. Pravdivtsev

1 month ago | analyticalsciencejournals.onlinelibrary.wiley.com | Josh Peters |Frank D. Sönnichsen |Jan-Bernd Hövener |Andrey N. Pravdivtsev

α Flip-angle αm Maximum flip-angle ADC Analog-to-digital-converter BB Broadband C Concentration d.i. Deionized dDNP Dissolution dynamic nuclear polarization FID Free induction decay GdCA Gadolinium-based contrast agent P Polarization RG Receiver gain RRT Receiver range threshold TR Repetition time Sm Maximum signal SNR Signal-to-noise-ratio 1 Introduction Nuclear magnetic resonance is a universal analytical method [1].

Dec 13, 2024 | nature.com | Lukas Kaltschnee |Andrey N. Pravdivtsev |Manuel Gehl |Gangfeng Huang |Christoph Riplinger |Frank Neese | +7 more

Hydrogenases are widespread metalloenzymes used for the activation and production of molecular hydrogen. Understanding the catalytic mechanism of hydrogenases can help to establish industrial (bio)catalytic hydrogen production and conversion. Here we show the observation of so-far undetectable intermediates of [Fe]-hydrogenase in its catalytic cycle. We observed these intermediates by applying a signal-enhancing NMR technique based on parahydrogen. Molecular hydrogen occurs as orthohydrogen or parahydrogen, depending on its nuclear spin state. We found that catalytic conversion of parahydrogen by the [Fe]-hydrogenase leads to notably enhanced NMR signals (parahydrogen-induced polarization, PHIP). The observed signals encode information about how the [Fe]-hydrogenase binds hydrogen during catalysis. Our data support models of the catalytic mechanism that involve the formation of a hydride at the iron centre. Moreover, PHIP enabled studying the binding kinetics. This work demonstrates the hitherto unexploited power of PHIP to study catalytic mechanisms of hydrogenases. The catalytic mechanism of [Fe]-hydrogenases is not well understood. Now a signal-enhanced nuclear magnetic resonance method based on parahydrogen is introduced to study [Fe]-hydrogenase under turnover conditions in situ, revealing intermediates of the catalytic cycle.

Oct 22, 2024 | nature.com | Henri de Maissin |Andrey N. Pravdivtsev |Arne Brahms |Leif Schröder |Eduard Y Chekmenev |Rainer Herges

AbstractHyperpolarized 13C MRI visualizes real-time metabolic processes in vivo. In this study, we achieved high 13C polarization in situ in the bore of an MRI system for precursor molecules of most widely employed hyperpolarized agents: [1-13C]acetate and [1-13C]pyruvate ethyl esters in their perdeuterated forms, enhancing hyperpolarization lifetimes, hyperpolarized to P13C ≈ 28% at 80 mM concentration and P13C ≈ 19% at 10 mM concentration, respectively.

Jun 30, 2023 | pubs.acs.org | Arne Brahms |Andrey N. Pravdivtsev |Frank D. Sönnichsen |Lynn Thorns

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