γ-AApeptides-based Small Molecule Ligands That Disaggregate Human Islet Amyloid Polypeptide.

The abnormal folding and aggregation of functional proteins into amyloid is a typical feature of many age-related diseases, including Type II diabetes. Growing evidence has revealed that the prevention of aggregate formation in culprit proteins could retard the progression of amyloid diseases. Human Amylin, also known as human islet amyloid polypeptide (hIAPP), is the major factor for categorizing Type II diabetes as an amyloid disease. Specifically, hIAPP has a great aggregation potential, which always results in a lethal situation for the pancreas. Many peptide inhibitors have been constructed from the various segments of the full-length hIAPP peptide; however, only a few have their origin from the screening of combinatorial peptidomimetic library. In this study, based on HW-155, which was previously discovered from a one-bead-one compound (OBOC) library to inhibit Aß40 aggregation, we investigated eight (8) analogues and evaluated their amyloid-prevention capabilities for inhibiting fibrillization of hIAPP. Characterization studies revealed that all analogues of HW-155, as well as HW-155, were effective inhibitors of the fibril formation by hIAPP.

Sulfono-γ-AA modified peptides that inhibit HIV-1 fusion.

The utilization of bioactive peptides in the development of highly selective and potent pharmacological agents for the disruption of protein-protein interactions is appealing for drug discovery. It is known that HIV-1 entry into a host cell is through a fusion process that is mediated by the trimeric viral glycoprotein gp120/41, which is derived from gp160 through proteolytic processing. Peptides derived from the HIV gp41 C-terminus have proven to be potent in inhibiting the fusion process. These peptides bind tightly to the hydrophobic pocket on the gp-41 N-terminus, which was previously identified as a potential inhibitor binding site. In this study, we introduce modified 23-residue C-peptides, 3 and 4, bearing a sulfono-γ-AA residue substitution and hydrocarbon stapling, respectively, which were developed for HIV-1 gp-41 N-terminus binding. Intriguingly, both 3 and 4 were capable of inhibiting envelope-mediated membrane fusion in cell-cell fusion assays at nanomolar potency. Our study reveals that sulfono-γ-AA modified peptides could be used for the development of more potent anti-HIV agents.

Developments with investigating descriptors for antimicrobial AApeptides and their derivatives.

INTRODUCTION: The development of multidrug-resistant strains of bacteria resulting from prolonged treatment with conventional antibiotics has necessitated the need for continuous research for better antibiotic strategies. One of these alternatives is evolutionary antimicrobial peptides also known as host-defense peptides (HDPs). HDPs are an integral part of the innate defense system in multicellular eukaryotes. Although HDPs can largely circumvent the persistent problem of antibiotic resistance due to their bacteriolytic membrane mechanism, they have some drawbacks including a low activity profile and protease instability. AApeptides have recently been introduced as a new class of peptidomimetics with resistance to proteolysis, improved activity profile, and limitless possibilities for structural diversity. Furthermore, they have shown excellent antimicrobial activity. Areas covered: This review updates the reader on the latest developments of antimicrobial AApeptides, the various derivatizations, and their development for antimicrobial applications. The most recent findings on the heterogeneous γ-AA backbone are also outlined. Expert opinion: AApeptides have found diverse applications in antimicrobial studies. AApeptides are believed to exhibit bactericidal properties by imitating the membranolytic action of HDPs. They have shown broad-spectrum antimicrobial activity and are active against medicinally relevant drug-resistant pathogens. AApeptides and their derivatives could gain therapeutic relevance in the design and development of antibiotic agents.

Supersnowflakes: Stepwise Self-Assembly and Dynamic Exchange of Rhombus Star-Shaped Supramolecules.

With the goal of increasing the complexity of metallo-supramolecules, two rhombus star-shaped supramolecular architectures, namely, supersnowflakes, were designed and assembled using multiple 2,2':6',2″-terpyridine (tpy) ligands in a stepwise manner. In the design of multicomponent self-assembly, ditopic and tritopic ligands were bridged through Ru(II) with strong coordination to form metal-organic ligands for the subsequent self-assembly with a hexatopic ligand and Zn(II). The combination of Ru(II)-organic ligands with high stability and Zn(II) ions with weak coordination played a key role in the self-assembly of giant heteroleptic supersnowflakes, which encompassed three types of tpy-based organic ligands and two metal ions. With such a stepwise strategy, the self-sorting of individual building blocks was prevented from forming the undesired assemblies, e.g., small macrocycles and coordination polymers. Furthermore, the intra- and intermolecular dynamic exchange study of two supersnowflakes by NMR and mass spectrometry revealed the remarkable stability of these giant supramolecular complexes.

Direct Self-Assembly of a 2D and 3D Star of David.

Two- and three-dimensional metallosupramolecules shaped like a Star of David were synthesized by the self-assembly of a tetratopic pyridyl ligand with a 180° diplatinum(II) motif and PdII ions, respectively. In contrast to other strategies, such as template-directed synthesis and stepwise self-assembly, this design enables the formation of 2D and 3D structures in one step and high yield. The structures were characterized by both one-dimensional (1 H, 13 C, 31 P) and two-dimensional (COSY, NOESY, DOSY) NMR spectroscopy, ESI-MS, ion-mobility mass spectrometry (IM-MS), AFM, and TEM. The stabilities of the 2D and 3D structures were measured and compared by gradient tandem mass spectrometry (gMS2 ). The high stability of the 3D Star of David was correlated to its high density of coordination sites (DOCS).

Structure and Function of AApeptides.

The intrinsic drawbacks encountered in bioactive peptides in chemical biology and biomedical sciences have diverted research efforts to the development of sequence-specific peptidomimetics that are capable of mimicking the structure and function of peptides and proteins. Modifications in the backbone and/or the side chain of peptides have been explored to develop biomimetic molecular probes or drug leads for biologically important targets. To expand the family of oligomeric peptidomimetics to facilitate their further application, we recently developed a new class of peptidomimetics, AApeptides based on a chiral peptide nucleic acid backbone. AApeptides are resistant to proteolytic degradation and amenable to enormous chemical diversification. Moreover, they could mimic the primary structure of peptides and also fold into discrete secondary structure such as helices and turn-like structures. Furthermore, they have started to show promise in applications in material and biomedical sciences. Herein, we highlight the structural design and some function of AApeptides and present our perspective on their future development.