D-Peptide and D-Protein Technology: Recent Advances, Challenges, and Opportunities

Total chemical protein synthesis provides access to entire D-protein enantiomers enabling unique applications in molecular biology, structural biology, and bioactive compound discovery. Key enzymes involved in the central dogma of molecular biology have been prepared in their D-enantiomeric forms facilitating the development of mirror-image life. Crystallization of a racemic mixture of L- and D-protein enantiomers provides access to high-resolution X-ray structures of polypeptides. Additionally, D-enantiomers of protein drug targets can be used in mirror-image phage display allowing discovery of non-proteolytic D-peptide ligands as lead candidates. This review discusses the unique applications of D-proteins including the synthetic challenges and opportunities.

Single-Shot Solid-Phase Synthesis of Full-Length H2 Relaxin Disulfide Surrogates

Chemical synthesis of insulin superfamily proteins (ISPs) has recently been widely studied to develop next-generation drugs. Separate synthesis of multiple peptide fragments and tedious chain-to-chain folding are usually encountered in these studies, limiting accessibility to ISP derivatives. Here we report the finding that insulin superfamily proteins (e.g. H2 relaxin, insulin itself, and H3 relaxin) incorporating a pre-made diaminodiacid bridge at A-B chain terminal disulfide can be easily and rapidly synthesized by a single-shot automated solid-phase synthesis and expedient one-step folding. Our new H2 relaxin analogues exhibit almost identical structures and activities when compared to their natural counterparts. This new synthetic strategy will expediate production of new ISP analogues for pharmaceutical studies.

Antiviral Peptides with in vivo Activity: Development and Modes of Action

The viral pandemic has resulted in a growing demand for antiviral drugs. The existing small-molecule antiviral drugs are limited, due to their incidence of drug resistance and adverse side effects. As potential drugs, antiviral peptides have the benefits of high activity, high stability, and few side effects. Furthermore, the diversity of acquisition methods allows antiviral peptides to be quickly designed and yielded. The drug properties (such as high bioavailability and in vivo stability) of antiviral peptides can be improved by the developed modifications. Currently, two peptide antiviral drugs have been approved for the treatment of acquired immunodeficiency syndrome (AIDS). Many antiviral peptides have entered clinical trials for the treatment of diseases caused by viruses. In addition, new antiviral peptides are continuously being identified and validated against virus infections. Given the benefits of antiviral peptides, they will become major antiviral drugs to combat new outbreaks caused by unknown viruses in the future. This review provides an overview of recent developments in antiviral peptides with in vivo activity.