Laplace NMR (LNMR) consists of relaxation and diffusion measurements providing detailed information about molecular motion and interaction. Here we demonstrate that ultrafast single- and multidimensional LNMR experiments, based on spatial encoding, are viable with low-field, single-sided magnets with an inhomogeneous magnetic field. This approach shortens the experiment time by one to two orders of magnitude relative to traditional experiments, and increases the sensitivity per unit time by a factor of three. The reduction of time required to collect multidimensional data opens significant prospects for mobile chemical analysis using NMR. Particularly tantalizing is future use of hyperpolarization to increase sensitivity by orders of magnitude, allowed by single-scan approach.
Flavonoids are polyphenolic small molecules that are abundant in plant products and are largely recognized for their beneficial health effects. Possessing both antioxidant and prooxidant properties, flavonoids have complex behavior in biological systems. The presented work investigates the intersection between the biological activity of flavonoids and their interactions with copper ions. Copper is required for the proper functioning of biological systems. As such, dysregulation of copper is associated with metabolic disease states such as diabetes and Wilson’s disease. There is evidence that flavonoids bind copper ions, but the biological implications of their interactions remain unclear. Better understanding these interactions will provide insight into the mechanisms of flavonoids’ biological behavior and can inform potential therapeutic targets. We employed a variety of spectroscopic techniques to study flavonoid-Cu(II) binding and radical scavenging activities. We identified structural moieties important in flavonoid-copper interactions which relate to ring substitution but not the traditional structural subclassifications. The biological effects of the investigated flavonoids specifically on copper trafficking were assessed in knockout yeast models as well as in human hepatocytes. The copper modulating abilities of strong copper-binding flavonoids were largely influenced by the relative hydrophobicities. Combined, these spectroscopic and biological data help elucidate the intricate nature of flavonoids in affecting copper transport and open avenues to inform dietary recommendations and therapeutic development.
The development of bioluminescence‐based tools has seen steady growth in the field of chemical biology over the past few decades ranging in uses from reporter genes to assay development and targeted imaging. More recently, coelenterazine‐utilizing luciferases such as Gaussia, Renilla, and the engineered nano‐luciferases have been utilized due to their intense luminescence relative to firefly luciferin/luciferase. The emerging importance of these systems warrants investigations into the components that affect their light production. Previous work has reported that one marine luciferase, Gaussia, is potently inhibited by copper salt. The mechanism for inhibition was not elucidated but was hypothesized to occur via binding to the enzyme. In this study, we provide the first report of a group of nonhomologous marine luciferases also exhibiting marked decreases in light emission in the presence of copper (II). We investigate the mechanism of action behind this inhibition and demonstrate that the observed copper inhibition does not stem from a luciferase interaction but rather the chemical oxidation of imidazopyrazinone luciferins generating inert, dehydrated luciferins.
Laplace NMR (LNMR) consists of relaxation and diffusion measurements providing detailed information about molecular motion and interaction. Here we demonstrate that ultrafast single-and multidimensional LNMR experiments, based on spatial encoding, are viable with low-field, singlesided magnets with an inhomogeneous magnetic field. This approach shortens the experiment time by one to two orders of magnitude relative to traditional experiments,and increases the sensitivity per unit time by af actor of three.T he reduction of time required to collect multidimensional data opens significant prospects for mobile chemical analysis using NMR. Particularly tantalizing is future use of hyperpolarization to increase sensitivity by orders of magnitude,allowed by singlescan approach.Nuclear magnetic resonance (NMR) spectroscopy is one of the most powerful and versatile tools in chemical analysis, [1] and is widely exploited in medicine as magnetic resonance imaging (MRI).[2] Single-sided magnets for NMR, first introduced over two decades ago, [3] solve three major problems associated with traditional high-field NMR experiments: cost, immobility,a nd sample size restrictions.S ingle-sided hardware is roughly an order of magnitude less expensive than its high-field counterpart. Single-sided magnets small size and low weight make them portable,a nd their open geometry allows for measurement of arbitrarily sized samples, including building materials, [4] paintings and other cultural heritage objects, [5] and skin; [6] they are also commonly used in well-logging. [7] One major downside to single-sided magnets is that their magnetic fields are strongly inhomogeneous,p reventing the observation of high-resolution NMR spectra. Impressive steps have been taken toward collecting high-resolution spectra in inhomogeneous fields.[8] However,d espite their inhomogeneity,s ingle-sided magnets still facilitate T 1 and T 2 relaxation as well as diffusion measurements.These measurements reveal details of molecular motion, explore interactions of nuclei with their microscopic environments,a nd can ultimately provide chemical information via these parameters. [1,3,9] Relaxation and diffusion data consist of exponentially decaying components,a nd the distribution of diffusion coefficients or relaxation times can be extracted from the experimental data by an inverse Laplace transformation. [10] Consequently,these methods are referred to as Laplace NMR (LNMR).As with traditional NMR spectroscopy,the resolution and information content of LNMR can be enhanced by am ultidimensional approach. [10,11] Multidimensional LNMR deals with the correlation of relaxation times and/or diffusion coefficients with one another;i tc an also measure chemical exchange via these observables.T his method has only recently entered routine use,f ollowing the development of as ufficiently reliable and robust multidimensional Laplace inversion algorithm in 2002.[12] Multidimensional LNMR measurements can also be performed in inhomogeneous fields,i ncluding those ...
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