ABSTRACT
The recent report by Fan et al alleged that the ProPerDP method is inadequate for the detection of protein persulfidation. Upon careful evaluation of their work, we conclude that the claim made by Fan et al is not supported by their data, rather founded in methodological shortcomings. It is understood that the ProPerDP method generates a mixture of cysteine-containing and non-cysteine-containing peptides. Instead, Fan et al suggested that the detection of non-cysteine-containing peptides indicates nonspecific alkylation at noncysteine residues. However, if true, then such peptides would not be released by reduction and therefore not appear as products in the reported workflow. Moreover, the authors' biological assessment of ProPerDP using Escherichia coli mutants was based on assumptions that have not been confirmed by other methods. We conclude that Fan et al did not rigorously assess the method and that ProPerDP remains a reliable approach for analyses of protein per/polysulfidation.
ABSTRACT
A selection of nine derivatives of teicoplanin pseudoaglycon were tested in vitro against clinical vancomycin-resistant Enterococcus strains possessing vanA, vanB or both genes. The bacteria were characterized by PCR for the identification of their resistance genes. The tested compounds contain lipoic acid, different carbohydrates and aryl groups as lipophilic moieties. About one-third of the teicoplanin-resistant strains were shown to be susceptible to one or more of the glycopeptide derivatives.
Subject(s)
Anti-Bacterial Agents/pharmacology , Enterococcus/drug effects , Teicoplanin/pharmacology , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Bacterial Proteins/genetics , Carbon-Oxygen Ligases/genetics , Drug Resistance, Bacterial/genetics , Enterococcus/genetics , Microbial Sensitivity Tests , Polymerase Chain Reaction , Teicoplanin/chemical synthesis , Teicoplanin/chemistry , Vancomycin/pharmacology , Vancomycin ResistanceABSTRACT
A series of lipophilic teicoplanin pseudoaglycon derivatives, including alkyl-, aryl-, calixarene- and protected sugar-containing conjugates, were prepared using azide-alkyne click chemistry. Out of the conditions applied, the CuSO4-ascorbate reagent system proved to be more efficient than the Cu(I)I-Et3N-mediated reaction. Some of the new compounds have high in vitro activity against glycopeptide-resistant Gram-positive bacteria, including vanA-positive Enterococcus faecalis. A few of them also display promising in vitro anti-influenza activity.