Short-lived calcium carbonate precursors observed in situ via Bullet-dynamic nuclear polarization.

The discovery of (meta)stable pre-nucleation species (PNS) challenges the established nucleation-and-growth paradigm. While stable PNS with long lifetimes are readily accessible experimentally, identifying and characterizing early-stage intermediates with short lifetimes remains challenging. We demonstrate that species with lifetimes ≪ 5 s can be characterized by nuclear magnetic resonance spectroscopy when boosted by 'Bullet' dynamic nuclear polarization (Bullet-DNP).

Branched Polymeric Prenucleation Assemblies Initiate Calcium Phosphate Precipitation.

The formation of crystalline calcium phosphate (CaP) has recently gained ample attention as it does not follow the classic nucleation-and-growth mechanism of solid formation. Instead, the precipitation mechanisms can involve numerous intermediates, including soluble prenucleation species. However, structural features, stability, and transformation of such solution-state precursors remain largely undisclosed.

Hyperpolarized nuclear Overhauser enhancement of alanine methyl groups by doubly relayed proton exchange.

Hyperpolarized water in dissolution dynamic nuclear polarization (dDNP) experiments has emerged as a promising method for enhancing nuclear magnetic resonance (NMR) signals, particularly in studies of proteins and peptides. Herein, we focus on the application of "proton exchange-doubly relayed" nuclear Overhauser effects (NOE) from hyperpolarized water to achieve positive signal enhancement of methyl groups in the side chain of an alanine-glycine peptide. In particular, we show a cascade hyperpolarization transfer.

An Atomistic View on the Mechanism of Diatom Peptide-Guided Biomimetic Silica Formation.

Deciphering nature's remarkable way of encoding functions in its biominerals holds the potential to enable the rational development of nature-inspired materials with tailored properties. However, the complex processes that convert solution-state precursors into solid biomaterials remain largely unknown. In this study, an unconventional approach is presented to characterize these precursors for the diatom-derived peptides R5 and synthetic Silaffin-1A (synSil-1A).

Unified understanding of the breakdown of thermal mixing dynamic nuclear polarization: The role of temperature and radical concentration.

We reveal an interplay between temperature and radical concentration necessary to establish thermal mixing (TM) as an efficient dynamic nuclear polarization (DNP) mechanism. We conducted DNP experiments by hyperpolarizing widely used DNP samples, i.e.

NMR-identification of the interaction between BRCA1 and the intrinsically disordered monomer of the Myc-associated factor X.

The breast cancer susceptibility 1 (BRCA1) protein plays a pivotal role in modulating the transcriptional activity of the vital intrinsically disordered transcription factor MYC. In this regard, mutations of BRCA1 and interruption of its regulatory activity are related to hereditary breast and ovarian cancer (HBOC). Interestingly, so far, MYC's main dimerization partner MAX (MYC-associated factor X) has not been found to bind BRCA1 despite a high sequence similarity between both oncoproteins.

Biphasic NMR of Hyperpolarized Suspensions-Real-Time Monitoring of Solute-to-Solid Conversion to Watch Materials Grow.

Nuclear magnetic resonance (NMR) spectroscopy is a key method for the determination of molecular structures. Due to its intrinsically high (, atomistic) resolution and versatility, it has found numerous applications for investigating gases, liquids, and solids. However, liquid-state NMR has found little application for suspensions of solid particles as the resonances of such systems are excessively broadened, typically beyond the detection threshold.

Constraining and Modifying Peptides Using Pd-Mediated Cysteine Allylation.

Over the past decades, several strategies for inducing and stabilizing secondary structure formation in peptides have been developed to increase their proteolytic stability and their binding affinity to specific interaction partners. Here, we report how our recently introduced chemoselective Pd-catalyzed cysteine allylation reaction can be extended to stapling and how the resulting alkene-containing staples themselves can be further modified to introduce additional probes into such stabilized peptides. The latter is demonstrated by introducing a fluorophore as well as a PEG moiety into different stapled peptides using bioorthogonal thiol-ene and Diels-Alder reactions.

Missing Pieces in Structure Puzzles: How Hyperpolarized NMR Spectroscopy Can Complement Structural Biology and Biochemistry.

Structure determination lies at the heart of many biochemical research programs. However, the "giants": X-ray diffraction, electron microscopy, molecular dynamics simulations, and nuclear magnetic resonance, among others, leave quite a few dark spots on the structural pictures drawn of proteins, nucleic acids, membranes, and other biomacromolecules. For example, structural models under physiological conditions or of short-lived intermediates often remain out of reach of the established experimental methods.

Understanding Self-Assembly of Silica-Precipitating Peptides to Control Silica Particle Morphology.

The most advanced materials are those found in nature. These evolutionary optimized substances provide highest efficiencies, e.g.

Frémy's Salt as a Low-Persistence Hyperpolarization Agent: Efficient Dynamic Nuclear Polarization Plus Rapid Radical Scavenging.

Nuclear magnetic resonance (NMR) spectroscopy is a key technique for molecular structure determination in solution. However, due to its low sensitivity, many efforts have been made to improve signal strengths and reduce the required substrate amounts. In this regard, dissolution dynamic nuclear polarization (DDNP) is a versatile approach as signal enhancements of over 10 000-fold are achievable.

Nuclear Overhauser spectroscopy in hyperpolarized water - chemical magnetic exchange.

Dissolution dynamic nuclear polarization (dDNP) is a versatile hyperpolarization technique to boost signal intensities in nuclear magnetic resonance (NMR) spectroscopy. The possibility to dissolve biomolecules in a hyperpolarized aqueous buffer under mild conditions has recently widened the scope of NMR by dDNP. The water-to-target hyperpolarization transfer mechanisms remain yet unclear, not least due to an often-encountered dilemma of dDNP experiments: The strongly enhanced signal intensities are accompanied by limited structural information as data acquisition is restricted to short time series of only one-dimensional spectra or a single correlation spectrum.

Identification of the Allosteric Binding Site for Thiazolopyrimidine on the C-Type Lectin Langerin.

Langerin is a mammalian C-type lectin expressed on Langerhans cells in the skin. As an innate immune cell receptor, Langerin is involved in coordinating innate and adaptive immune responses against various incoming threats. We have previously reported a series of thiazolopyrimidines as murine Langerin ligands.

Toward protein NMR at physiological concentrations by hyperpolarized water-Finding and mapping uncharted conformational spaces.

Nuclear magnetic resonance (NMR) spectroscopy is a key method for determining the structural dynamics of proteins in their native solution state. However, the low sensitivity of NMR typically necessitates nonphysiologically high sample concentrations, which often limit the relevance of the recorded data. We show how to use hyperpolarized water by dissolution dynamic nuclear polarization (DDNP) to acquire protein spectra at concentrations of 1 μM within seconds and with a high signal-to-noise ratio.

Inversion of Hyperpolarized C NMR Signals through Cross-Correlated Cross-Relaxation in Dissolution DNP Experiments.

Dissolution dynamic nuclear polarization (DDNP) is a versatile tool to boost signal amplitudes in solution-state nuclear magnetic resonance (NMR) spectroscopy. For DDNP, nuclei are spin-hyperpolarized "" in a dedicated DNP device and then transferred to an NMR spectrometer for detection. Dramatic signal enhancements can be achieved, enabling shorter acquisition times, real-time monitoring of fast reactions, and reduced sample concentrations.

Hyperpolarized water as universal sensitivity booster in biomolecular NMR.

NMR spectroscopy is the only method to access the structural dynamics of biomolecules at high (atomistic) resolution in their native solution state. However, this method's low sensitivity has two important consequences: (i) typically experiments have to be performed at high concentrations that increase sensitivity but are not physiological, and (ii) signals have to be accumulated over long periods, complicating the determination of interaction kinetics on the order of seconds and impeding studies of unstable systems. Both limitations are of equal, fundamental relevance: non-native conditions are of limited pharmacological relevance, and the function of proteins, enzymes and nucleic acids often relies on their interaction kinetics.

Conformational selection of vasopressin upon V receptor binding.

The neuropeptide vasopressin (VP) and its three G protein-coupled receptors (VR, VR and VR) are of high interest in a wide array of drug discovery programs. VR is of particular importance due to its cardiovascular functions and diverse roles in the central nervous system. The structure-activity relationships underpinning ligand-receptor interactions remain however largely unclear, hindering rational drug design.

Residue-resolved monitoring of protein hyperpolarization at sub-second time resolution.

Signal-enhancement techniques for NMR spectroscopy are important to amplify the weak resonances provided by nuclear spins. Recently, 'hyperpolarization' techniques have been intensively investigated. These provide nuclear spin states far from equilibrium yielding strong signal boosts up to four orders of magnitude.

Evaporation-Induced Self-Assembly of Small Peptide-Conjugated Silica Nanoparticles.

Self-assembly processes guide disordered molecules or particles into long-range organized structures due to specific supramolecular interactions among the building entities. Herein, we report a unique evaporation-induced self-assembly (EISA) strategy for four different silica nanoparticle systems obtained through peptide functionalization of the particle surface. First, covalent peptide-silica coupling was investigated in detail, starting with the grafting of a single amino acid (L-serine) and expanded to specific small peptides (up to four amino acids) and transferred to different particle types (MCM-48-type MSNs, solid nanoparticles, and newly developed virus-like nanoparticles).

Formation and Evolution of Nanoscale Calcium Phosphate Precursors under Biomimetic Conditions.

Simulated body fluids (SBFs) that mimic human blood plasma are widely used media for studies in an extensive array of research fields, from biomineralization to surface and corrosion sciences. We show that these solutions undergo dynamic nanoscopic conformational rearrangements on the timescale of minutes to hours, even though they are commonly considered stable or metastable. In particular, we find and characterize nanoscale inhomogeneities made of calcium phosphate (CaP) aggregates that emerge from homogeneous SBFs within a few hours and evolve into prenucleation species (PNS) that act as precursors in CaP crystallization processes.

Nature-inspired dimerization as a strategy to modulate neuropeptide pharmacology exemplified with vasopressin and oxytocin.

Vasopressin (VP) and oxytocin (OT) are cyclic neuropeptides that regulate fundamental physiological functions four G protein-coupled receptors, VR, VR, VR, and OTR. Ligand development remains challenging for these receptors due to complex structure-activity relationships. Here, we investigated dimerization as a strategy for developing ligands with novel pharmacology.

A novel sample handling system for dissolution dynamic nuclear polarization experiments.

We present a system for facilitated sample vitrification, melting, and transfer in dissolution dynamic nuclear polarization (DDNP) experiments. In DDNP, a sample is typically hyperpolarized at cryogenic temperatures before dissolution with hot solvent and transfer to a nuclear magnetic resonance (NMR) spectrometer for detection in the liquid state. The resulting signal enhancements can exceed 4 orders of magnitude.

How to assess the structural dynamics of transcription factors by integrating sparse NMR and EPR constraints with molecular dynamics simulations.

We review recent advances in modeling structural ensembles of transcription factors from nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopic data, integrated with molecular dynamics (MD) simulations. We focus on approaches that confirm computed conformational ensembles by sparse constraints obtained from magnetic resonance. This combination enables the deduction of functional and structural protein models even if nuclear Overhauser effects (NOEs) are too scarce for conventional structure determination.

Ingredient-Dependent Extent of Lipid Oxidation in Margarine.

This study reports the impact of margarine-representative ingredients on its oxidative stability and green tea extract as a promising antioxidant in margarine. Oil-in-water emulsions received much attention regarding factors that influence their oxidative stability, however, water-in-oil emulsions have only been scarcely investigated. Margarine, a widely consumed water-in-oil emulsion, consists of 80-90% fat and is thermally treated when used for baking.

Hyperpolarized NMR Metabolomics at Natural C Abundance.

Metabolomics plays a pivotal role in systems biology, and NMR is a central tool with high precision and exceptional resolution of chemical information. Most NMR metabolomic studies are based on H 1D spectroscopy, severely limited by peak overlap. C NMR benefits from a larger signal dispersion but is barely used in metabolomics due to ca.