A concise synthesis of (2 S ,4 R )- and (2 S ,4 S )-4-methylglutamic acid

Proline Analogues

Within the canonical repertoire of the amino acid involved in protein biogenesis, proline plays a unique role as an amino acid presenting a modified backbone rather than a side-chain. Chemical structures that mimic proline but introduce changes into its specific molecular features are defined as proline analogues. This review article summarizes the existing chemical, physicochemical, and biochemical knowledge about this peculiar family of structures. We group proline analogues from the following compounds: substituted prolines, unsaturated and fused structures, ring size homologues, heterocyclic, e.g., pseudoproline, and bridged proline-resembling structures. We overview (1) the occurrence of proline analogues in nature and their chemical synthesis, (2) physicochemical properties including ring conformation and cis/trans amide isomerization, (3) use in commercial drugs such as nirmatrelvir recently approved against COVID-19, (4) peptide and protein synthesis involving proline analogues, (5) specific opportunities created in peptide engineering, and (6) cases of protein engineering with the analogues. The review aims to provide a summary to anyone interested in using proline analogues in systems ranging from specific biochemical setups to complex biological systems.

Total Synthesis of Malacidin A by β-Hydroxyaspartic Acid Ligation-Mediated Cyclization and Absolute Structure Establishment

The development of novel antibiotics is critical to combating the growing emergence of drug-resistant pathogens. Malacidin A is a new member of the calcium-dependent antibiotic (CDAs) family with activity against antibiotic-resistant pathogens. Its mode of action is distinct from classical CDAs. However, the absolute structure of malacidin A has not been established. Herein, the total syntheses of malacidin A and its analogues are reported by a combination of Fmoc-based solid-phase peptide synthesis (SPPS) and β-hydroxyaspartic acid ligation-mediated peptide cyclization. The total synthesis enabled us to establish the absolute configuration of malacidin A, which is in agreement with those for natural malacidin A confirmed by advanced Marfey's analysis in our study.

Spirocyclic systems derived from pyroglutamic acid

The synthesis and likely conformational structure of rigid spirocyclic bislactams and lactam-lactones derived from pyroglutamic acid, and their suitability as lead structures for applications in drug development programmes using cheminformatic analysis, has been investgated.