Search

Phenolic compounds undergo radical coupling under oxidizing conditions. Silicone oils were modified with eugenol using hydrosilylation to create oils and elastomers that exhibited antioxidant activity due to the presence of phenols, as shown by DPPH and other oxidative assays. At room temperature, phenolic coupling was not observed, as judged by lack of changes in viscosity or formation of gels. By contrast, peroxide oxidants at temperatures above 90 °C led to crosslinked materials whose physical properties (related to crosslink density) correlated with eugenol content, equivalents of peroxide added and reaction time. The product elastomers were also efficient antioxidants, although there was some attenuation of activity in higher crosslinked materials, consistent with diverse radical recombination processes. [ABSTRACT FROM AUTHOR]

Goldenes Arin? Gold ‐ Arin ‐ Komplexe werden als Übergangszustände in dualen Gold ‐ katalysierte Cyclisierungen von cis ‐ Endiinen angenommen (siehe Schema; DCE=1,2 ‐ Dichlorethan); sie werden besser beschrieben als ortho ‐ Aurophenyl ‐ Kationen, die mit schwachen Nucleophile reagieren und leichte intramolekulare Insertionen in C(sp3) ‐ H ‐ Bindungen eingehen. Mit der Methode wurden Indane, kondensierte Heteroarene und Phenolderivate auf einfache Weise hergestellt. [ABSTRACT FROM AUTHOR]

Proteolysis is one of the most important protein post-translational modifications (PTMs) that influences the functions, activities, and structures of nearly all proteins during their lifetime. To facilitate the targeted identification of low-abundant proteolytic products, we devised a strategy incorporating a novel biotinylated reagent PFP (pentafluorophenyl)-Rink-biotin to specifically target, enrich and identify proteolytic N-termini. Within the PFP-Rink-biotin reagent, a mass spectrometry (MS)-cleavable feature was designed to assist in the unambiguous confirmation of the enriched proteolytic N-termini. The proof-of-concept study was performed with multiple standard proteins whose N-termini were successfully modified, enriched and identified by a signature ion (SI) in the MS/MS fragmentation, along with the determination of N-terminal peptide sequences by multistage tandem MS of the complementary fragment generated after the cleavage of MS-cleavable bond. For large-scale application, the enrichment and identification of protein N-termini from Escherichia coli cells were demonstrated, facilitated by an in-house developed NTermFinder bioinformatics workflow. We believe this approach will be beneficial in improving the confidence of identifying proteolytic substrates in a native cellular environment. [ABSTRACT FROM AUTHOR]