Organoautocatalyzed transamination metathesis of cyclic tertiary amines is disclosed as a high-yielding, scalable reaction that proceeds under mild, catalyst-free conditions. It operates via a multi-....

DNA-encoded Libraries (DEL) are increasingly used for small molecule drug discovery. While millions to billions of compounds can simultaneously be screened, the following validation of hits represent...

Pentraxin-2 (PTX-2), also known as Serum Amyloid P component, functions as an immunoregulatory glycoprotein and plays a crucial role in fibrotic diseases such as idiopathic pulmonary fibrosis (IPF). ...

Reduced pressure for electrospray ionization of native proteins narrows peak widths and increases signal. This straightforward add-on to existing native MS platforms improves performance in challengi...

Cross-linking mass spectrometry (XL-MS) has become a powerful tool in structural biology for investigating protein structure, dynamics, and interactomics. However, short-range cross-links, defined as...

A facile photochemical, one-pot synthesis of highly functionalized 1-aminotetralins derivatives (> 70 examples) from readily accessible o-alkyl and o-formyl aryl silylimines with olefins is described...

See proteins fold in living cells. A mass spectrometry platform integrates rapid online buffer exchange and electrophoretic separation to provide sub-second snapshots of protein dynamics directly in ....

Cross-linking mass spectrometry (XL-MS) enables the mapping of protein-protein interactions on the cellular level. When applied to all compartments of mitochondria, the sheer number of cross-links an...

Innovations in spatial omics technologies applied to human tissues have led to breakthrough discoveries in various diseases, including cancer. Two of these approaches - spatial transcriptomics and sp....

Validating biomarkers of disease is necessary for clinical use. The Health Surveillance Panel (83 peptides from 57 proteins) was developed as a PRM assay and evaluated using the Stellar-MS platform. ...

A proximity-induced, mass-encoded activity-based protein profiling (ABPP) approach transfers a MALDI-detectable α-cyano-4-hydroxycinnamic acid (CHCA) tag directly to active proteases. This tag enables the direct, multiplexed, and quantitative detection of enzyme activity in complex proteomes without enrichment or purification. ABSTRACT Conventional activity-based probes in activity-based protein profiling (ABPP) require enrichment or reporter tags for detection, which limits sensitivity and multiplexing. Here, we present an enrichment-free chemoproteomic approach that enables direct mass spectrometric detection by Matrix-Assisted Laser Desorption/Ionization (MALDI) of active proteases. An active-site–directed affinity probe transfers, through a proximity-induced reaction, a MALDI-detectable α-cyano-4-hydroxycinnamic acid (CHCA) tag exclusively to catalytically active forms of matrix metalloproteases (MMPs). The CHCA label enhances ionization efficiency and markedly improves signal-to-noise ratios, allowing confident identification of CHCA-labelled peptides under discriminating analytical conditions. Each active metalloprotease is thereby, associated with a distinct set of CHCA signature peptides, defining its activity fingerprint. This workflow achieves multiplexed and quantitative activity profiling of MMPs, directly in complex proteomes. This design expands ABPP into the mass spectrometry domain and establishes a robust platform for activity-based enzyme detection.

Glutaredoxins (Grx) rapidly reduce glutathione polysulfides (GSSnSG) to glutathione hydroper/polysulfides (GSSnH) or GSSnH to hydrogen (poly)sulfides (H2Sn). Reduction of glutathionylated glutaredoxins by reduced glutathione (GSH) yields glutathione disulfide (GSSG). Thus, steady-state concentrations of glutathione (hydro)per/polysulfides should be tightly controlled in compartments containing active glutaredoxins and high GSH concentrations. ABSTRACT Hydropersulfides have gained attention as excellent biochemical nucleophiles and membrane-protective radical scavengers. They form perthiyl radicals, which terminate radical chain reactions through self-recombination, yielding polysulfides. It is currently unknown exactly how polysulfides are subsequently reduced. Using stopped–flow kinetic measurements in combination with mass spectrometry, we show that the model class I glutaredoxin from Plasmodium falciparum (PfGrx) rapidly reduces the polysulfides glutathione trisulfide (GS3G) and tetrasulfide (GS4G), yielding glutathionylated PfGrx and the corresponding glutathione hydropersulfide (GSSH) and hydrotrisulfide (GS3H). The second-order rate constants of these reductions ≥107 M−1s−1 are even slightly higher than for glutathione disulfide (GSSG). In contrast, PfGrx was inactive or only moderately active toward cystine or cysteine trisulfide. GSSH and GS3H are further reduced by PfGrx with second-order rate constants on the order of 106−107 M−1s−1, yielding glutathionylated PfGrx and hydrogen sulfide (H2S) or hydrogen disulfide (H2S2), respectively. Thus, glutaredoxins specifically recognize the glutathione moiety of glutathione (hydro)per/polysulfides. Since reduced glutathione (GSH) rapidly reduces glutathionylated glutaredoxins, glutathione (hydro)per/polysulfides are efficiently converted to GSSG and H2S or the corresponding hydrogen polysulfides. As a consequence, the steady-state concentration of glutathione (hydro)per/polysulfides should be tightly controlled in subcellular compartments containing active glutaredoxins and high GSH concentrations.

We introduce a novel chemical derivatisation strategy for the UV-activated detection of elusive metabolites. Incorporation of a tocopherol-active chromophore allows for the detection of tagged analytes as photoionised radical cations, selectively induced by a 266 nm laser. Furthermore, high spatially resolved imaging of metabolites has been demonstrated across multiple tissue types. ABSTRACT Matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) has been widely adopted for the spatially resolved mapping of chemical composition within biological tissues. However, inherent limitations in ionisation efficiencies limit the scope of analyte detection. Currently, methods to enhance molecular coverage have focused on chemical derivatisation of target analyte classes or post-ionisation techniques, namely, laser post-ionisation (MALDI-2). Previously, we observed that under reduced laser fluence conditions, MALDI-2 can be utilised to selectively enhance photoionisation of aromatic analytes. Leveraging these observations, we have conducted a proof-of-concept study to establish a conceptually novel class of derivatisation reagents, employing a tocopherol active chromophore O-linked succinimide (TAC/OS) for the selective derivatisation of primary amines. Using TAC/OS, amino metabolites were selectively detected as the derivatised radical cations in the presence of MALDI-2. Across three tissue types, over 30 metabolites were detected and localised, including 20 amino acids alongside neurotransmitters such as γ-aminobutyric acid (GABA) and dopamine. Imaging at 10 µm pixel size revealed minimal delocalisation, allowing for MSI at near single-cell resolution. Furthermore, we demonstrated the ability of the developed protocol on late-stage pancreatic cancer xenografts.

Stereocontrolled syntheses of chiral (oxa)helicene-indenido half-sandwich (Rh) or ansa-metallocene (Fe) complexes were developed. The enantio- and diastereopure half-sandwich Rh(III) complexes were u...

We introduce a novel chemical derivatisation strategy for the UV-activated detection of elusive metabolites. Incorporation of a tocopherol-active chromophore allows for the detection of tagged analytes as photoionised radical cations, selectively induced by a 266 nm laser. Furthermore, high spatially resolved imaging of metabolites has been demonstrated across multiple tissue types. ABSTRACT Matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) has been widely adopted for the spatially resolved mapping of chemical composition within biological tissues. However, inherent limitations in ionisation efficiencies limit the scope of analyte detection. Currently, methods to enhance molecular coverage have focused on chemical derivatisation of target analyte classes or post-ionisation techniques, namely, laser post-ionisation (MALDI-2). Previously, we observed that under reduced laser fluence conditions, MALDI-2 can be utilised to selectively enhance photoionisation of aromatic analytes. Leveraging these observations, we have conducted a proof-of-concept study to establish a conceptually novel class of derivatisation reagents, employing a tocopherol active chromophore O-linked succinimide (TAC/OS) for the selective derivatisation of primary amines. Using TAC/OS, amino metabolites were selectively detected as the derivatised radical cations in the presence of MALDI-2. Across three tissue types, over 30 metabolites were detected and localised, including 20 amino acids alongside neurotransmitters such as γ-aminobutyric acid (GABA) and dopamine. Imaging at 10 µm pixel size revealed minimal delocalisation, allowing for MSI at near single-cell resolution. Furthermore, we demonstrated the ability of the developed protocol on late-stage pancreatic cancer xenografts.