External link: https://twitter.com/ciqususc/status/1398252322191458306

Abstract: Transcription factors (TFs) have a remarkable role in the homeostasis of the organisms and there is a growing interest in how they recognize and interact with specific DNA sequences. TFs recognize DNA using a variety of structural motifs. Among those, the ribbon-helix-helix (RHH) proteins, exemplified by the MetJ and ARC repressors, form dimers that insert antiparallel β-sheets into the major groove of DNA. A great chemical challenge consists of using the principles of DNA recognition by TFs to design minimized peptides that maintain the DNA affinity and specificity characteristics of the natural counterparts. In this context, a peptide mimic of an antiparallel β-sheet is very attractive since it can be obtained by a single peptide chain folding in a β-hairpin structure and can be as short as 14 amino acids or less. Herein, we designed eight linear and two cyclic dodeca-peptides endowed with β-hairpins. Their DNA binding properties have been investigated using fluorescence spectroscopy together with the conformational analysis through circular dichroism and solution NMR. We found that one of our peptides, peptide 6, is able to bind DNA, albeit without sequence selectivity. Notably, it shows a topological selectivity for the major groove of the DNA which is the interaction site of ARC and many other DNA-binding proteins. Moreover, we found that a type I’ β-hairpin folding pattern is a favorite peptide structure for interaction with the B-DNA major groove. Peptide 6 is a valuable lead compound for the development of novel analogs with sequence selectivity.

External link: https://www.sciencedirect.com/science/article/abs/pii/S0045206821002133

Abstract: Low‐valent cobalt complexes equipped with chiral ligands can efficiently promote highly enantioselective (3+2) cycloadditions of alkyne‐tethered alkylidenecyclopropanes. The annulation allows to assemble bicyclic systems containing five‐membered rings in good yields and with excellent enantiomeric ratios. We also present a mechanistic discussion based on experimental and computational data, which support the involvement of Co(I)/Co(III) catalytic cycles

External link: https://onlinelibrary.wiley.com/doi/10.1002/anie.202015202

External link: https://twitter.com/MetBioCat/status/1305921149973327872

Abstract: Here, we report the application of surface-enhanced Raman scattering (SERS) spectroscopy as a rapid and practical tool for assessing the formation of coordinative adducts between nucleic acid guanines and ruthenium polypyridyl reagents. The technology provides a practical approach for the wash-free and quick identification of nucleic acid structures exhibiting sterically accessible guanines. This is demonstrated for the detection of a quadruplex-forming sequence present in the promoter region of the c-myc oncogene, which exhibits a non-paired, reactive guanine at a flanking position of the G-quartets.

External link: https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.0c02148