Chemical analysis mass spectrom Publications

The reliance of modern technology growth on lanthanides presents dual challenges: securing sustainable sources from natural or recycled materials and reducing environmental harm from waste discharge. However, the similar ionic radii, oxidation states, and binding affinities of Ln³⁺ ions hinder their nondestructive detection in mixtures. Furthermore, the overlap of spectroscopic signals and the inapplicability for opaque solutions limit the harness of luminescent sensors for differentiating one Ln³⁺ from another. Here, we introduce ¹⁹F-paramagnetic guest exchange saturation transfer magnetic resonance fingerprinting (¹⁹F-paraGEST MRF), a rapid signal acquisition, encoding, and analysis approach for detecting specific Ln³⁺ in mixtures. Based on a small-sized experimental ¹⁹F-paraGEST data set, we generated a de novo dictionary of ∼2500 combinations of Ln³⁺ mixtures, resulting in ∼7,000,000 simulated ¹⁹F-paraGEST MRF patterns of different Ln³⁺ concentrations. This dictionary was later used for computational pattern recognition of experimental NMR signal evolutions (\u201cfingerprints\u201d), utilizing a rapid computational approach executable on a standard laptop within seconds. Hence, fast and reliable multiplexed lanthanide detection in complex mixtures was enabled. Demonstrated through the analysis of lanthanides content of permanent magnets from a hard disk drive, this MR-based method paves the way for broader applications of lanthanide detection in murky, nontransparent mixtures and further exploration of supramolecular sensors in diverse scenarios.

Caspase family proteases and Toll/interleukin-1 receptor (TIR)-domain proteins have central roles in innate immunity and regulated cell death in humans. We describe a bacterial immune system comprising both a caspase-like protease and a TIR-domain protein. We found that the TIR protein, once it recognizes phage invasion, produces the previously unknown immune signaling molecule adenosine 5-diphosphate-cyclo[N7:1]-ribose (N7-cADPR). This molecule specifically activates the bacterial caspase-like protease, which then indiscriminately degrades cellular proteins to halt phage replication. The TIR-caspase defense system, which we denote as type IV Thoeris, is abundant in bacteria and efficiently protects against phage propagation. Our study highlights the diversity of TIR-produced immune signaling molecules and demonstrates that cell death regulated by proteases of the caspase family is an ancient mechanism of innate immunity.

Metal-capped molecular hosts are unique in supramolecular chemistry, benefitting from the inner cavity's hydrophobic nature and the metal center's electrochemical properties. It is shown here that the paramagnetic properties of the metals in lanthanide-capped cyclodextrins (Ln-α-CDs and Ln-β-CDs) are a convenient NMR indicator for different populations of host-guest complexes in a given solution. The paramagnetic guest exchange saturation transfer (paraGEST) method was used to study the exchange dynamics in systems composed of Ln-α-CDs or Ln-β-CDs with fluorinated guests, revealing multiple co-existing populations of host-guest complexes exclusively in solutions containing Ln-β-CDs. The enhanced spectral resolution of paraGEST, achieved by a strong pseudo contact shift induction, revealed that different molecular guests can adopt multiple orientations within Ln-β-CDs' cavities and, in contrast, only a single orientation inside Ln-α-CDs. Thus, paraGEST, which can significantly improve NMR detectability and spectral resolution of host-guest systems that experience fast exchange dynamics, is a convenient tool for studying supramolecular systems of metal-capped molecular hosts.

Although the mode of action of the ribosomes, the multi-component universal effective protein-synthesis organelles, has been thoroughly explored, their mere appearance remained elusive. Our earlier comparative structural studies suggested that a universal internal small RNA pocket-like segment called by us the protoribosome, which is still embedded in the contemporary ribosome, is a vestige of the primordial ribosome. Herein, after constructing such pockets, we show using the "fragment reaction" and its analyses by MALDI-TOF and LC-MS mass spectrometry techniques, that several protoribosome constructs are indeed capable of mediating peptide-bond formation. These findings present strong evidence supporting our hypothesis on origin of life and on ribosome's construction, thus suggesting that the protoribosome may be the missing link between the RNA dominated world and the contemporary nucleic acids/proteins life.