A novel N-terminal degradation reaction of peptides via N-amidination

Stabilizing Pseudouridimycin: Synthesis, RNA Polymerase Inhibitory Activity, and Antibacterial Activity of Dipeptide-Modified Analogues

Pseudouridimycin (PUM) is a microbially produced C-nucleoside dipeptide that selectively targets the nucleotide addition site of bacterial RNA polymerase (RNAP) and that has a lower rate of spontaneous resistance emergence relative to current drugs that target RNAP. Despite its promising biological profile, PUM undergoes relatively rapid decomposition in buffered aqueous solutions. Here, we describe the synthesis, RNAP-inhibitory activity, and antibacterial activity of chemically stabilized analogues of PUM. These analogues feature targeted modifications that mitigate guanidine-mediated hydroxamate bond scission. A subset of analogues in which the central hydroxamate is replaced with amide or hydrazide isosteres retain the antibacterial activity of the natural product.

Total synthesis and chemical stability of pseudouridimycin

We report the chemical synthesis of pseudouridimycin (1), an antimicrobial natural product that potently and selectively inhibits bacterial RNA polymerase. Chemical stability studies revealed intramolecular hydroxamate bond scission to be...

Amide Bond Activation of Biological Molecules

Amide bonds are the most prevalent structures found in organic molecules and various biomolecules such as peptides, proteins, DNA, and RNA. The unique feature of amide bonds is their ability to form resonating structures, thus, they are highly stable and adopt particular three-dimensional structures, which, in turn, are responsible for their functions. The main focus of this review article is to report the methodologies for the activation of the unactivated amide bonds present in biomolecules, which includes the enzymatic approach, metal complexes, and non-metal based methods. This article also discusses some of the applications of amide bond activation approaches in the sequencing of proteins and the synthesis of peptide acids, esters, amides, and thioesters.

Peptide self-cleavage at a canaline residue: application to a solubilizing tag system for native chemical ligation

Canaline (Can) is a non-proteinogenic amino acid containing an aminooxy group in its side chain. Can-containing peptides can be synthesized by standard Fmoc SPPS using Fmoc-Can(2-Cl-Trt). Here, for the first time, a Can residue within a peptide sequence was found to spontaneously cleave the main chain amide bond under slightly acidic conditions (pH 4-5). Contrastingly, Can-containing peptides are completely stable under the acidic conditions for HPLC purification (pH ca. 2) and under the neutral conditions for native chemical ligation (NCL). Taking advantage of these unique pH-dependent properties of Can, a novel solubilizing tag system for NCL-mediated protein synthesis using (Lys/Arg)n-Can was developed.