Biocatalysis of d,l-Peptide Nanofibrillar Hydrogel

Abstract

<jats:p>Self-assembling peptides are attracting wide interest as biodegradable building blocks to achieve functional nanomaterials that do not persist in the environment. Amongst the many applications, biocatalysis is gaining momentum, although a clear structure-to-activity relationship is still lacking. This work applied emerging design rules to the heterochiral octapeptide sequence His–Leu–DLeu–Ile–His–Leu–DLeu–Ile for self-assembly into nanofibrils that, at higher concentration, give rise to a supramolecular hydrogel for the mimicry of esterase-like activity. The peptide was synthesized by solid-phase and purified by HPLC, while its identity was confirmed by 1H-NMR and electrospray ionization (ESI)-MS. The hydrogel formed by this peptide was studied with oscillatory rheometry, and the supramolecular behavior of the peptide was investigated with transmission electron microscopy (TEM) analysis, circular dichroism (CD) spectroscopy, thioflavin T amyloid fluorescence assay, and attenuated total reflectance (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The biocatalytic activity was studied by monitoring the hydrolysis of p-nitrophenyl acetate (pNPA) at neutral pH, and the reaction kinetics followed an apparent Michaelis–Menten model, for which a Lineweaver–Burk plot was produced to determine its enzymatic parameters for a comparison with the literature. Finally, LC–MS analysis was conducted on a series of experiments to evaluate the extent of, if any, undesired peptide acetylation at the N-terminus. In conclusion, we provide new insights that allow gaining a clearer picture of self-assembling peptide design rules for biocatalysis.</jats:p>

Amyloids as Building Blocks for Macroscopic Functional Materials: Designs, Applications and Challenges

“…Carlomagno et al designed an amyloid-like octapeptide-based hydrogel with catalytic activities. The His–Leu– D Leu–Ile–His–Leu– D Leu–Ile octapeptide relied on the hydrophobicity of leucine and isoleucine to self-assemble and was found to form hydrogel at 10 mM, which is much lower compared to previously reported tripeptide [ 146 ].…”

Supramolecular assemblies of histidine-containing peptides with switchable hydrolase and peroxidase activities through Cu(ii) binding and co-assembling

“…Compared with other peptides containing hydrophilic groups (e.g., Asp, His, Ser, Arg and Lys) around the His residue, FH with a hydrophobic Phe group beside the His residue could form an appropriate hydrophobic binding pocket through supramolecular interactions, which could facilitate substrate binding (K M = 0.93 mM) and hydrolysis. 35,36 Besides acting as a general base to trigger the hydrolysis reaction, the histidine residue within self-assembling peptides can also coordinate with Cu 2+ ions. 37,38 Molecular interactions between His-containing peptides and Cu 2+ ions were investigated by CD and FTIR spectroscopies.…”

“…, Asp, His, Ser, Arg and Lys) around the His residue, FH with a hydrophobic Phe group beside the His residue could form an appropriate hydrophobic binding pocket through supramolecular interactions, which could facilitate substrate binding ( K M = 0.93 mM) and hydrolysis. 35,36…”

Heterochiral tetrapeptide self‐assembly into hydrogel biomaterials for hydrolase mimicry

“…21 Recently, using this strategy, also the selfassembling sequence L-His-L-Leu-D-Leu-L-Ile-L-His-L-Leu-D-Leu-L-Ile was reported to gel, but despite the presence of two His residues, the catalytic performance was only slightly better than L-His-D-Phe-D-Phe under analogous conditions. 22 In light of these observations, this study aims at evaluating the self-assembling and catalytic activity of two heterochiral tetrapeptides bearing the catalytic motif Ser-His (Scheme 2), that is, D-Ser-D-His-L-Phe-L-Phe and D-Ser-D-His-L-Phe-L-Phe-NH 2 (amidated at the C-terminus). This choice for amino acid chirality was dictated by the need to have both Ser and His with the same stereoconfiguration as was shown to be beneficial in previous studies for the catalytic performance.…”