An efficient method has been developed for the chemoselective cysteine modification of unprotected peptides and proteins in aqueous media through the formation of a vinyl sulfide linkage by using electron-deficient alkynes, including alkynoic amides, esters and alkynones. The terminal alkynone-modified peptides could be converted back into the unmodified peptides (81% isolated yield) by adding thiols under mild conditions. The usefulness of this thiol-assisted cleavage of the vinyl sulfide linkage in peptides has been exemplified by the enrichment of a cysteine-containing peptide (71% recovery) from a mixture of cysteine-containing and non-cysteine-containing peptides.
Dioxiranes generated in situ from pyruvates (alpha-keto esters) and Oxone have been found to be environmentally friendly oxidizing agents for disinfection. These oxidizing agents were highly effective for destruction of various strains of bacteria, fungi, and bacterial endospores in a wide temperature range with exceptional stability. Notably, by using an aqueous solution of methyl pyruvate (1a) and Oxone/NaHCO3, complete destruction of bacteria such as Staphylococcus aureus and fungus Penicillium corylophilum was achieved within 5 min at 20 degrees C at neutral pH. Highly chemical-resistant bacterial endospores of Bacillus cereus could also be destroyed. The high antibacterial activity of 1a could be attributed to its strong electron-withdrawing alpha-ester group.
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