Acid-responsive fibrillation and urease-assisted defibrillation of phenylalanine: a transient supramolecular hydrogel.

The aggregation of proteins and peptides into fibrils is associated with many neurodegenerative diseases in humans, including Alzheimer's disease, Parkinson's disease and non-neurological type-II diabetes. A better understanding of the fibril formation process and defibrillation using biochemical tools is highly important for therapeutics. Under physiological conditions, acidic pH promotes the formation of toxic fibrils.

Conformational Heterogeneity and Self-Assembly of α,β,γ-Hybrid Peptides Containing Fenamic Acid: Multistimuli-Responsive Phase-Selective Gelation.

The effect of fenamic acid-α-aminoisobutyric acid corner motif in α,β,γ-hybrid peptides has been reported. From X-ray single-crystal diffraction studies, it is observed that Phe-containing peptide has an "S"-shaped conformation that is stabilized by two consecutive intramolecular N-H···N hydrogen bonds. However, the tyrosine analogue peptide has an "S"-shaped conformation, which is stabilized by consecutive intramolecular six-member N-H···N and seven-member N-H···O hydrogen bonds.

Pentapeptide Nanoreactor as a Platform for Halogenations, Diels-Alder Reaction, and Morita-Baylis-Hillman Reaction.

A pentapeptide nanoreactor has been designed and synthesized as a platform to carry out the traditional organic reactions such as bromination, iodination, cycloaddition, and condensation reactions. The pentapeptide Boc-Phe-Phe-Aib-Phe-Phe-OMe with a supramolecular helical structure and π-rich channel provides nanoconfinements and thus facilitates the organic reactions. Bromination and iodination of aniline take place without any halogen carrier (Lewis acid) in the pentapeptide platform.

Urea-Appended Amino Acid To Vitalize Yeast Growth, Enhance Fermentation, and Promote Ethanol Production.

The development of sustainable protocols for enhancing the production of ethanol is highly important for its utilization in automotive transportation and energy sector. Up to 15% ethanol can blend with diesel to make e-diesel that can be used in fuel compression ignition engine. Urea-modified amino acids can be used as a very good vitalizer for yeast (, Baker's yeast (ATCC 204508)) growth and thus promote ethanol production.

α,ε-Hybrid Peptide Foldamers: Self-Assembly of Peptide with Trans Carbon-Carbon Double Bonds in the Backbone and Its Saturated Analogue.

The effect of geometrically rigid trans α,β-unsaturated ε-amino acids on the structure, folding, and assembly of α,ε-hybrid peptide foldamers has been reported. From single-crystal diffraction analysis, the unsaturated tetrapeptide has stapler-pin-like structure but without intramolecular hydrogen bond. The asymmetric unit has two molecules that are stabilized by multiple intermolecular hydrogen bonding interactions as well as π-π stacking interactions between the aromatic rings of 3-aminocinnamic acid.

Synergistic Tricolor Emission-Based White Light from Supramolecular Organic-Inorganic Hybrid Gel.

The development of engineered hybrid systems by encapsulating nanoparticles in gel scaffolds and their synergistic effects are highly crucial for the fabrication of advanced functional materials. Herein, a series of dipeptides containing an aromatic amino acid at the N-terminal and an aliphatic amino acid at the C-terminal were synthesized and studied. Among them, only the dipeptide l-Phe-l-Val can form both hydro- and organogelator, depending on the N- and C-terminal protecting groups.

Formation of toroids by self-assembly of an α-α corner mimetic: supramolecular cyclization.

An α-α corner mimetic self-assembles to form a rod-like supramolecular structure which bends and closes end-to-end like a cyclization reaction to form uniform toroids. Each peptide fragment containing l-leucine, α-aminoisobutyric acid (Aib) and l-tyrosine forms rigid 3 helical structures stabilized by multiple intramolecular N-HO hydrogen bonds. Two 3 helices are connected by the spacer 3-aminomethyl-benzylamine and maintain an angular distance of 120° and therefore mimic the α-α corner motif of a protein super secondary structure.

Synthesis and structural investigation of 2-aminomethyl-3-(4-methoxy-phenyl)-propionic acid containing a peptide analogue of the amyloidogenic AS(6-7) sequence: inhibition of fibril formation.

The incorporation of a single β-amino acid moiety in a highly amyloidogenic peptide sequence resulted in the complete inhibition of amyloid fibril formation. The Boc-l-Phe-l-Leu-OMe sequence 1, which has sequence identity with the N-terminal AS(6-7) of the non-immunoglobulin amyloid fibril protein AS, which is responsible for rheumatoid arthritis, self-associates to produce fibrils. The d-Phe analogue peptide 2 shows an elongated ribbon-like morphology.