Residual-Chemical-Shift-Anisotropy-Based Enantiodifferentiation in Lyotropic Liquid Crystalline Phases Based on Helically Chiral Polyacetylenes.

Anisotropic NMR spectroscopy, revealing residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) has emerged as a powerful tool to determine the configurations of synthetic and complex natural compounds. The deduction of the absolute in addition to the relative configuration is one of the primary goals in the field. Therefore, the investigation of the enantiodiscriminating capabilities of chiral alignment media becomes essential.

Multistage Detection of Tetrodotoxin Traces in Collected in El Salvador.

This study describes a multistage methodology to detect minute amounts of tetrodotoxin in fishes, a plan that may be broadened to include other marine organisms. This methodology was applied to porcupinefish () collected in Punta Chiquirín, El Salvador. A three-stage approach along with post-acquisition processing was employed, to wit: (a) Sample screening by selected reaction monitoring (HPLC-MS/MS-SRM) analyses to quickly identify possible toxin presence via a LC/MS/MS API 3200 system with a triple quadrupole; (b) HPLC-HRFTMS-full scan analyses using an ion trap-Orbitrap spectrometer combined with an MZmine 2-enhanced dereplication-like workflow to collect high-resolution mass spectra; and (c) HPLC-HRMS analyses.

Anle138b interaction in α-synuclein aggregates by dynamic nuclear polarization NMR.

Small molecules that bind to oligomeric protein species such as membrane proteins and fibrils are of clinical interest for development of therapeutics and diagnostics. Definition of the binding site at atomic resolution via NMR is often challenging due to low binding stoichiometry of the small molecule. For fibrils and aggregation intermediates grown in the presence of lipids, we report atomic-resolution contacts to the small molecule at sub nm distance via solid-state NMR using dynamic nuclear polarization (DNP) and orthogonally labelled samples of the protein and the small molecule.

Antimicrobial Diterpene Alkaloids from an Sponge Collected in the Yucatán Peninsula.

Three new diterpene alkaloids, (+)-8-epiagelasine T (), (+)-10-epiagelasine B (), and (+)-12-hydroxyagelasidine C (), along with three known compounds, (+)--agelasine F (), (+)-agelasine B (), and (+)-agelasidine C (), were isolated from the sponge , collected on the coasts of the Yucatán Peninsula (Mexico). Their chemical structures were elucidated by 1D and 2D NMR spectroscopy, HRESIMS techniques, and a comparison with literature data. Although the synthesis of (+)--agelasine F () has been previously reported, this is the first time that it was isolated as a natural product.

Structure and Absolute Configuration of Phenanthro-perylene Quinone Pigments from the Deep-Sea Crinoid .

Two new water-soluble phenanthroperylene quinones, gymnochrome H () and monosulfated gymnochrome A (), as well as the known compounds gymnochrome A () and monosulfated gymnochrome D () were isolated from the deep-sea crinoid , which had been collected in the deep sea of Japan. The structures of the compounds were elucidated by spectroscopic analysis including HRMS, 1D H and C NMR, and 2D NMR. The absolute configuration was determined by ECD spectroscopy, analysis of -couplings and ROE contacts, and DFT calculations.

Biomolecular phase separation through the lens of sodium-23 NMR.

Phase separation is a fundamental physicochemical process underlying the spatial arrangement and coordination of cellular events. Detailed characterization of biomolecular phase separation requires experimental access to the internal environment of dilute and especially condensed phases at high resolution. In this study, we take advantage from the ubiquitous presence of sodium ions in biomolecular samples and present the potentials of Na NMR as a proxy to report the internal fluidity of biomolecular condensed phases.

Author Correction: Relative configuration of micrograms of natural compounds using proton residual chemical shift anisotropy.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Relative configuration of micrograms of natural compounds using proton residual chemical shift anisotropy.

3D molecular structure determination is a challenge for organic compounds or natural products available in minute amounts. Proton/proton and proton/carbon correlations yield the constitution. J couplings and NOEs oftentimes supported by one-bond H,C residual dipolar couplings (RDCs) or by C residual chemical shift anisotropies (RCSAs) provide the relative configuration.

The Fish Pathogen Under Iron Deprivation Produces the Siderophore Piscibactin.

is the causative agent of vibriosis, mainly in salmonid fishes, and its virulence mechanisms are still not completely understood. In previous works we demonstrated that possess several iron uptake mechanisms based on heme utilization and siderophore production. The aim of the present work was to confirm the production and utilization of piscibactin as a siderophore by .

Hypalocrinins, Taurine-Conjugated Anthraquinone and Biaryl Pigments from the Deep Sea Crinoid Hypalocrinus naresianus.

Five new water-soluble amido- and aminoanthraquinone pigments, hypalocrinins A-E (1-5), the new amidoanthraquinone biaryls hypalocrinin F (6) and hypalocrinin G (7), and the known compounds 6-bromoemodic acid (8), crinemodin (9), and crinemodin sulfate (10) were isolated from the deep sea crinoid Hypalocrinus naresianus collected off Japan. The structures of the compounds were elucidated by NMR spectroscopy and mass spectrometry. Amido- and aminoquinones are quite unusual among natural products.

The Siderophore Piscibactin Is a Relevant Virulence Factor for Favored at Low Temperatures.

causes vibriosis, a hemorrhagic septicaemia that affects many cultured marine fish species worldwide. Two catechol siderophores, vanchrobactin and anguibactin, were previously identified in this bacterium. While vanchrobactin is a chromosomally encoded system widespread in all pathogenic and environmental strains, anguibactin is a plasmid-encoded system restricted to serotype O1 strains.

AHL-lactonase expression in three marine emerging pathogenic Vibrio spp. reduces virulence and mortality in brine shrimp (Artemia salina) and Manila clam (Venerupis philippinarum).

Bacterial infectious diseases produced by Vibrio are the main cause of economic losses in aquaculture. During recent years it has been shown that the expression of virulence genes in some Vibrio species is controlled by a population-density dependent gene-expression mechanism known as quorum sensing (QS), which is mediated by the diffusion of signal molecules such as N-acylhomoserine lactones (AHLs). QS disruption, especially the enzymatic degradation of signalling molecules, known as quorum quenching (QQ), is one of the novel therapeutic strategies for the treatment of bacterial infections.

Secreted Citrate Serves as Iron Carrier for the Marine Pathogen subsp .

subsp () is a that has a wide pathogenic potential against many marine animals and also against humans. Some strains of this bacterium acquire iron through the siderophore vibrioferrin. However, there are virulent strains that do not produce vibrioferrin, but they still give a strong positive reaction in the CAS test for siderophore production.

A Transmissible Plasmid-Borne Pathogenicity Island Confers Piscibactin Biosynthesis in the Fish Pathogen Photobacterium damselae subsp. piscicida.

The fish pathogen Photobacterium damselae subsp. piscicida produces the siderophore piscibactin. A gene cluster that resembles the Yersinia high-pathogenicity island (HPI) encodes piscibactin biosynthesis.