Tristhiolato Pseudopeptides Bind Arsenic(III) in an AsS Coordination Environment Imitating Metalloid Binding Sites in Proteins.

The As binding of two NTA-based tripodal pseudopeptides, possessing three cysteine (ligand ) or d-penicillamine residues (ligand ) as potential coordinating groups for soft semimetals or metal ions, was studied by experimental (UV, CD, NMR, and ESI-MS) and theoretical (DFT) methods. All of the experimental data, obtained with the variation of the As:ligand concentration ratios or pH values in some instances, evidence the exclusive formation of species with an AsS-type coordination mode. The UV-monitored titration of the ligands with arsenous acid at pH = 7.

TmAlphaFold database: membrane localization and evaluation of AlphaFold2 predicted alpha-helical transmembrane protein structures.

AI-driven protein structure prediction, most notably AlphaFold2 (AF2) opens new frontiers for almost all fields of structural biology. As traditional structure prediction methods for transmembrane proteins were both complicated and error prone, AF2 is a great help to the community. Complementing the relatively meager number of experimental structures, AF2 provides 3D predictions for thousands of new alpha-helical membrane proteins.

PolarProtDb: A Database of Transmembrane and Secreted Proteins showing Apical-Basal Polarity.

Most cells in multicellular organisms are somehow asymmetric, polarized: maintaining separate membrane domains. Typical examples are the epithelial cells (apical-basal polarization), neurons (dendritic-axonal domains), or migratory cells (with a leading and a trailing edge). Here we present the most comprehensive database containing experimentally verified mammalian proteins that display polarized sorting or secretion, focusing on epithelial polarity.

Hg and Cd binding of a bioinspired hexapeptide with two cysteine units constructed as a minimalistic metal ion sensing fluorescent probe.

Hg and Cd complexation of a short hexapeptide, Ac-DCSSCY-NH (DY), was studied by pH-potentiometry, UV and NMR spectroscopy and fluorimetry in aqueous solutions and the Hg-binding ability of the ligand was also described in an immobilized form, where the peptides were anchored to a hydrophilic resin. Hg was demonstrated to form a 1 : 1 complex with the ligand even at pH = 2.0 while Cd coordination by the peptide takes place only above pH ∼ 3.

Interaction of Arsenous Acid with the Dithiol-Type Chelator British Anti-Lewisite (BAL): Structure and Stability of Species Formed in an Unexpectedly Complex System.

British anti-Lewisite (2,3-dimerkaptopropan-1-ol, dimercaprol, BAL) is one of the best-known chelator-type therapeutic agents against toxic metal ions and metalloids, especially arsenicals. Surprisingly, the mechanisms of action at the molecular level, as well as the coordination features of this traditional drug toward various arsenicals, are still poorly revealed. The present study on the interaction of arsenous acid (HAsO) with BAL, involving UV and NMR titrations, electrospray ionization mass spectrometry, and 2D NMR experiments combined with MP2 calculations, demonstrates that the reaction of HAsO with BAL at pH = 7.