On the hypothetical protein F154 of the TTV1 virus/Thermoproteus Tenax. Part II: Synthesis of the trieicosapeptide,corresponding to the protein sequence 79–101

Summary For the identification of a protein predicted by DNA sequence analysis of the TTV1 virus from the archaebacteriumThermoproteus tenax, the trieicosapeptide H-Thr-Pro-Thr-Pro-Thr-Pro-Thr-Tyr-Asp-Ile-Thr-Tyr-Val-Val-Phe-Asp-Val-Thr-Pro-Ser-Pro-Thr-Pro-OH, corresponding to the protein fragment 79–101, was prepared by conventional methods of peptide synthesis. This sequence portion may possibly represent a suitable protein specific immunepitope.

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Zur Hypothese eines TTV1 Virus/Thermoproteus tenax F154-Proteins. Teil II: Synthese des Protein-fragments 79–101

Zusammenfassung Für den Nachweis der Expression des Proteins F154 — nach einer Sequenzanalyse des Genoms des TTV1 Virus im ArchaebakteriumThermoproteus tenax postuliert — wurde das Peptid H-Thr-Pro-Thr-Pro-Thr-Pro-Thr-Tyr-Asp-Ile-Thr-Tyr-Val-Val-Phe-Asp-Val-Thr-Pro-Ser-Pro-Thr-Pro-OH (Proteinfragment 79–101) mit Hilfe konventioneller Peptidsynthese hergestellt. Diese Peptidsequenz sollte ein geeignetes proteinspezifisches Immunepitop darstellen.

     

Discovery of Chemicals to Either Clear or Indicate Amyloid Aggregates by Targeting Memory‐Impairing Anti‐Parallel Aβ Dimers

Amyloid‐β (Aβ) oligomers are implicated in Alzheimer disease (AD). However, their unstable nature and heterogeneous state disrupts elucidation of their explicit role in AD progression, impeding the development of tools targeting soluble Aβ oligomers. Herein parallel and anti‐parallel variants of Aβ(1–40) dimers were designed and synthesized, and their pathogenic properties in AD models characterized. Anti‐parallel dimers induced cognitive impairments with increased amyloidogenesis and cytotoxicity, and this dimer was then used in a screening platform. Through screening, two FDA‐approved drugs, Oxytetracycline and Sunitinib, were identified to dissociate Aβ oligomers and plaques to monomers in 5XFAD transgenic mice. In addition, fluorescent Astrophloxine was shown to detect aggregated Aβ in brain tissue and cerebrospinal fluid samples of AD mice. This screening platform provides a stable and homogeneous environment for observing Aβ interactions with dimer‐specific molecules.     

Synthesis of β3-amino acid and peptides from D-ribose

Synthesis of new β³-amino acid, peptides and conformational analysis are reported from d-ribose, using Wittig olefination and Aza-Michael addition.     

Self‐Assembled Cyclic d,l‐α‐Peptides as Generic Conformational Inhibitors of the α‐Synuclein Aggregation and Toxicity: In Vitro and Mechanistic Studies

Many peptides and proteins with large sequences and structural differences self‐assemble into disease‐causing amyloids that share very similar biochemical and biophysical characteristics, which may contribute to their cross‐interaction. Here, we demonstrate how the self‐assembled, cyclic d,l ‐α‐peptide CP‐2 , which has similar structural and functional properties to those of amyloids, acts as a generic inhibitor of the Parkinson′s disease associated α‐synuclein (α‐syn) aggregation to toxic oligomers by an ?off‐pathway“ mechanism. We show that CP‐2 interacts with the N‐terminal and the non‐amyloid‐β component region of α‐syn, which are responsible for α‐syn′s membrane intercalation and self‐assembly, thus changing the overall conformation of α‐syn. CP‐2 also remodels α‐syn fibrils to nontoxic amorphous species and permeates cells through endosomes/lysosomes to reduce the accumulation and toxicity of intracellular α‐syn in neuronal cells overexpressing α‐syn. Our studies suggest that targeting the common structural conformation of amyloids may be a promising approach for developing new therapeutics for amyloidogenic diseases.     

Water‐Insensitive Synthesis of Poly‐β‐Peptides with Defined Architecture

Biocompatible and proteolysis‐resistant poly‐β‐peptides have broad applications and are dominantly synthesized via the harsh and water‐sensitive ring‐opening polymerization of β‐lactams in a glovebox or using a Schlenk line, catalyzed by the strong base LiN(SiMe₃)₂. We have developed a controllable and water‐insensitive ring‐opening polymerization of β‐amino acid N‐thiocarboxyanhydrides (β‐NTAs) that can be operated in open vessels to prepare poly‐β‐peptides in high yields, with diverse functional groups, variable chain length, narrow dispersity and defined architecture. These merits imply wide applications of β‐NTA polymerization and resulting poly‐β‐peptides, which is validated by the finding of a HDP‐mimicking poly‐β‐peptide with potent antimicrobial activities. The living β‐NTA polymerization enables the controllable synthesis of random, block copolymers and easy tuning of both terminal groups of polypeptides, which facilitated the unravelling of the antibacterial mechanism using the fluorophore‐labelled poly‐β‐peptide.     

Rationally Designed CeNP@MnMoS4 Core‐Shell Nanoparticles for Modulating Multiple Facets of Alzheimer's Disease

Alzheimer's disease (AD) is a complicated multifactorial syndrome. Lessons have been learned through failed clinical trials that targeting multiple key pathways of the AD pathogenesis is necessary to halt the disease progression. Here, we construct core‐shell nanoparticles (CeNP@MnMoS₄) targeting multiple key pathways of the AD pathogenesis, including elimination of toxic metal ions, decrease of oxidative stress, and promotion of neurite outgrowth. The SOD activity and copper removal capacity of CeNP@MnMoS₄‐n (n represents the number of layers of MnMoS₄, n=1–5) was investigated in vitro. We found that CeNP@MnMoS₄‐3 made an excellent balance between SOD activity and copper removal capacity. The effect of CeNP@MnMoS₄‐3 on Cu²⁺‐induced Aβ aggregation was studied by gel electrophoresis, transmission electron microscope (TEM), and atomic force microscopy (AFM). Compared with MnMoS₄ or CeNP alone, a synergistic effect was observed. Moreover, CeNP@MnMoS₄‐3 promoted neurite outgrowth in a dose‐dependent manner. Taken together, the results reported in this work show the potential of new multifunctional core‐shell nanoparticles as AD therapeutics.     

A Glycosylated Cationic Block Poly(β‐peptide) Reverses Intrinsic Antibiotic Resistance in All ESKAPE Gram‐Negative Bacteria

Carbapenem‐resistant Gram‐negative bacteria (GNB) are heading the list of pathogens for which antibiotics are the most critically needed. Many antibiotics are either unable to penetrate the outer‐membrane or are excluded by efflux mechanisms. Here, we report a cationic block β‐peptide (PAS8‐b‐PDM12) that reverses intrinsic antibiotic resistance in GNB by two distinct mechanisms of action. PAS8‐b‐PDM12 does not only compromise the integrity of the bacterial outer‐membrane, it also deactivates efflux pump systems by dissipating the transmembrane electrochemical potential. As a result, PAS8‐b‐PDM12 sensitizes carbapenem‐ and colistin‐resistant GNB to multiple antibiotics in vitro and in vivo. The β‐peptide allows the perfect alternation of cationic versus hydrophobic side chains, representing a significant improvement over previous antimicrobial α‐peptides sensitizing agents. Together, our results indicate that it is technically possible for a single adjuvant to reverse innate antibiotic resistance in all pathogenic GNB of the ESKAPE group, including those resistant to last resort antibiotics.     

On the hypothetical protein F154 of the TTV1 virus/Thermoproteus Tenax. Part I: Synthesis of a dodecapeptide amide related to the protein sequence 73–84

Summary DNA sequence analysis of the virus TTV1 identified in archaebacteriumThermoproteus tenax revealed an open reading frame possibly encoding for a protein. To assess the expression of this hypothetical protein F154 via immunochemical methods, related synthetic fragments should allow for production of protein specific antisera. For this purpose the dodecapeptide amide H-Thr-Pro-Thr-Pro-Thr-Pro-Thr-Pro-Ser-Pro-Thr-Pro-NH₂ related to a characteristic repeat in the protein primary structure was prepared by conventional methods of peptide synthesis.Dedicated to Prof. Dr. Karl Schlögl on occasion of his 65th birthday     

Heavy‐Atom Labeled Transmembrane β‐Peptides: Synthesis,CD‐Spectroscopy,and X‐ray Diffraction Studies in Model Lipid Multilayer

Transmembrane β‐peptides are promising candidates for the design of well‐controlled membrane anchors in lipid membranes. Here, we present the synthesis of transmembrane β‐peptides with and without tryptophan anchors, as well as a novel iodine‐labeled d ‐β³‐amino acid. By using one or more of the heavy‐atom labeled amino acids as markers, the orientation of the helical peptide was inferred based on the electron‐density profile determined by X‐ray reflectivity. The β‐peptides were synthesized through manual Fmoc‐based solid‐phase peptide synthesis (SPPS) and reconstituted in unilamellar vesicles forming a right‐handed 3₁₄‐helix secondary structure, as shown by circular dichroism spectroscopy. We then integrated the β‐peptide into solid‐supported membrane stacks and carried out X‐ray reflectivity and grazing incidence small‐angle X‐ray scattering to determine the β‐peptide orientation and its effect on the membrane bilayers. These β‐peptides adopt a well‐ordered transmembrane motif in the solid‐supported model membrane, maintaining the basic structure of the original bilayer with some distinct alterations. Notably, the helical tilt angle, which accommodates the positive hydrophobic mismatch, induces a tilt of the acyl chains. The tilted chains, in turn, lead to a membrane thinning effect.     

Exploring Helical Folding in Oligomers of Cyclopentane-Based ϵ-Amino Acids: A Computational Study

The conformational preferences of oligopeptides of an ϵ-amino acid (2-((1R,3S)-3-(aminomethyl)cyclopentyl)acetic acid, Amc₅a) with a cyclopentane substituent in the C^β−C^γ−C^δ sequence of the backbone were investigated using DFT methods in chloroform and water. The most preferred conformation of Amc₅a oligomers (dimer to hexamer) was the H₁₆ helical structure both in chloroform and water. Four residues were found to be sufficient to induce a substantial H₁₆ helix population in solution. The Amc₅a hexamer adopted a stable left-handed (M)-2.3₁₆ helical conformation with a rise of 4.8 Å per turn. The hexamer of Ampa (an analogue of Amc₅a with replacing cyclopentane by pyrrolidine) adopted the right-handed mixed (P)-2.9_18/16 helical conformation in chloroform and the (M)-2.4₁₆ helical conformation in water. Therefore, hexamers of ϵ-amino acid residues exhibited different preferences of helical structures depending on the substituents in peptide backbone and the solvent polarity as well as the chain length.