Peptide-induced RAFT polymerization via an amyloid-ß17-20 -based chain transfer agent

Kumar, S., et al. Soft Matter, 2020, 16,6964-6968, DOI: 10.1039/D0SM01169J

We here describe the synthesis of a novel  peptide/polymer-conjugate, embedding the amyloid-β (Aβ) protein core sequence Leu-Val-Phe-Phe (LVFF, Aβ17-20) via RAFT polymerization. Based on a novel chain transfer-agent, the “grafting-from” approach effectively generates the well-defined peptide-polymer conjugates with appreciably high monomer conversion rate, resulting in mechanically stiffer peptide-functional cross-linked polymeric hydrogels. Reproduced by permission of The Royal Society of Chemistry 2020.

Bifunctional Peptide-Polymer Conjugates Based Fibers via a One-Pot Tandem Disulfide Reduction Coupled to a Thio-Bromo “Click” Reaction

Kumar, S., et al. ACS Omega, 2020, 5 (30) 19020-19028

In view of the potential applications of fibers towards material sciences and biomedicine, an effective synthetic strategy is described to construct the bi-headed peptide-conjugate FFFF-PEG-FFFF (Mn,GPC= 3800 g mol-1, Ɖ = 1.10) via a one-pot, tandem–disulfide-reduction coupled to a thio-bromo“click” reaction for supramolecular self-association in solution. The conjugate was investigated via transmission electron microscopy to exploit supramolecular fibril formation and solvent dependent structuring into macroscale fibers via fibril-fibril interactions and inter-fibril cross-linking induced bundling. This synthetic approach opens the way for a simplified synthesis of PEG-containing peptide conjugates. Copyright © 2020 American Chemical Society

Tuning layered superstructures in precision polymers.

Danke, V., et al. Scientific Reports 2020, 12119,

An approach to influence and control layered superstructures by varying the methylene sequence length between two consecutive functional groups in linear precision polymers containing 2,6-diaminopyridfine (DAP) group is presented. Occurrence of different layered structures depending on crystallization conditions, methylene sequence length as well as defect type is explained by a competition of H-interactions between the DAP groups and the van der Waal forces between the hydrophobic methylene groups. Reproduced with permission. Copyright© 2020, Springer Nature.

β-Turn mimetic synthetic peptides as amyloid-β aggregation inhibitors.

Deike, S., et al. Bioorganic Chemistry 2020,ASAP

Aggregation of amyloid peptides results in severe neurodegenerative diseases. We here report the preparation of beta-turn mimetic conjugates containing synthetic turn mimetic structures in the turn region of Aβ40 and Aβ16-35, replacing 2 amino acids in the turn-region G25 – K28. The structure of the turn mimic induces both, acceleration of fibrillation and the complete inhibition of fibrillation, confirming the importance of the turn region on the aggregation. Reproduced with permission. Copyright 2020© Elsevier B. V.

Thio-Bromo “Click” Reaction Derived Polymer–Peptide Conjugates for Their Self-Assembled Fibrillar Nanostructures.

Kumar, S., et al. Macromolecular Bioscience 2020,2000048,DOI:

The synthesis and self-assembly of peptide-polymer conjugates into fibrillar nanostructures are reported, based on the amyloidogenic peptide KLVFF. A strategy for rational synthesis of polymer?peptide conjugates is documented via tethering of the amyloidogenic peptide segment LVFF (Aβ17-20) and its modified derivative FFFF to the hydrophilic poly(ethylene glycol) monomethyl ether (mPEG) polymer via thio-bromo based “click” chemistry. The peptide-guided self-assembling behavior of the amphiphilic supramolecular materials is investigated exhibiting fibrillar nanostructure formation in binary aqueous solution mixture. Reproduced with permission. Copyright 2020©, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chirality Control of Screw-Sense in Aib-Polymers: Synthesis and Helicity of Amino Acid Functionalized Polymers.

Freudenberg, J., et al. ACS Macro Letters 2020, 686-692,

2-Aminoisobutyric acid (Aib) is an essential amino acid, leading to the formation of peptAibols as microbiologically active peptides and proteins. We here report on the ring-opening polymerization (ROP) of Aib-NCA (N-carboxy-anhydrides), enabling to prepare distinct Aib-polymers up to molecular weights of 1400 g/mol with precise end-group control. The attachment of chiral (D or L)-amino acids allows to systematically investigate the helical screw-sense of poly(Aib)n, resulting in chiral induction to form either left (M)- or right (P)-handed screw-senses. The approach is extended toward a switchable, chiral azo-headgroup, able to change chirality of the attached poly(Aib)n via a light-induced trigger. Reproduced with permission. Copyright 2020©, American Chemical Society.

Hybrid polymers bearing oligo-l-lysine(carboxybenzyl)s: synthesis and investigations of secondary structure.

Canalp, M., et al. RSC Advances 2020,10 (3), 1287-1295,DOI:

Hybrid polymers of peptides resembling (partially) folded protein structures are promising materials in biomedicine, especially in view of folding-interactions between different segments. In this study polymers bearing repetitive peptidic folding elements, composed of N-terminus functionalized bis-ω-ene-functional oligo-l-lysine(carboxybenzyl(Z))s (Lysn) with repeating units (n) of 3, 6, 12, 24 and 30 were successfully synthesized to study their secondary structure introduced by conformational interactions between their chains. We can demonstrate the influence of chain length of the generated polymers on the formation of secondary structures by comparing Lysnswith varying n values to the ADMET-polymers in a helicogenic solvent. Reproduced by permission of The Royal Society of Chemistry.

Synthesis and Mechanochemical Activity of Peptide-Based Cu(I) Bis(N-Heterocyclic Carbene) Complexes.

Funtan, S., et al. Biomimetics 2019,4 (1), 24,DOI:

With the class of shock-absorbing proteins, nature created some of the most robust materials combining both mechanical strength and elasticity.  Here, we report on the synthesis of two different latent mechanophoric copper(I) bis(N-heterocyclic carbene) complexes bearing either two carboxyl groups or two amino groups which allow conjugation reactions with either the N- or the C-terminus of amino acids or peptides. Mechanochemical activation by ultrasound showed conversions in the copper(I)-catalyzed alkyne-azide “click” reaction (CuAAC) up to 9.9% proving the potential application for the time and spatial controlled CuAAC.

Multisegmented Hybrid Polymer Based on Oligo-Amino Acids: Synthesis and Secondary Structure in Solution and in the Solid State.

Freudenberg, J., et al. Macromolecules 2019,52 (12), 4534-4544,DOI:

The synthesis of multisegmented polymers containing repetitive oligo-(BnAspn, BnGlun) sequences separated by methylene units and their secondary structure formation in solution and in the solid state are reported. Combining ring-opening polymerization (ROP) of N-carboxyanhydrides with postfunctionalization of the respective N-terminus yields the oligo-( BnAsp3, BnAsp10, BnGlu3, and BnGlu10) sequences bearing terminal vinyl groups on either side of the polymer chain by preparative gel permeation chromatography generate polymers of a precise degree of polymerization (n = 3, 10; m = 1–136). β-sheet conformation is identified as the thermodynamically more stable conformation, as supported by our experiments in the solid state and in solution. Reproduced with permission. Copyright 2019©, American Chemical Society.

Modulation of amyloid β peptide aggregation by hydrophilic polymers.

Evgrafova, Z., et al. Physical Chemistry Chemical Physics 2019,21 (37), 20999-21006,DOI:

A substantial number of diseases leading to loss of neurologic functions such as Morbus Alzheimer, Morbus Parkinson, or Chorea Huntington are related to the fibrillation of particular amyloidogenic peptides. We investigated amyloid-beta 1–40 peptide (Aβ1–40) fibrillation in mixture with thermoresponsive poly(oligo(ethylene glycol)macrylates), in which the polymer’s hydrophobicity is tuned by variation of the number of ethylene glycol-units in the side chain (m = 1–9), the end groups (B = butoxy; C = carboxy; D = dodecyl; P = pyridyldisulfide). The polymers were prepared via RAFT-polymerization. Less hydrophilic polymers (m = 1–2) were able to both decrease and elongate the lag (tlag) and characteristic times (tchar) of Aβ1–40 fibril formation in dependence of their end groups, molecular mass and hydrophilicity. Reproduced with permission from the PCCP Owner Societies.