Xianzhang Bu

An improved deblocking agent for direct Fmoc solid-phase synthesis of peptide thioesters

To synthesize peptide thioesters directly on a solid support for use as substrate analogues for thioesterases in non-ribosomal peptide synthases, we modified a reagent compatible with Fmoc solid-phase peptide synthesis that efficiently removes the protecting group while keeping the thioester intact. The deprotecting reagent, consisting of DBU and HOBt, was successfully used to prepare a decapeptide in high yield.

Substrate spectrum of tyrocidine thioesterase probed with randomized peptide N-acetylcysteamine thioesters

Apparent kinetic constants k(cat) and K(m) were determined for tyrocidine thioesterase (TycC TE) using randomized peptide N-acetylcysteamine thioesters as substrate analogues. The enzyme has been found to be adequately active for the synthesis of positional-scanning libraries for novel antibiotic screening with reduced k(cat)/K(m) in the range of 2 to 82 folds lower than that of the wild-type sequence