Periodic introduction of aromatic units in polypeptides via chemoenzymatic polymerization to yield specific secondary structures with high thermal stability

Efficacy, physicochemical and processing properties of oat peptides prepared via ultrasonication-assisted organic acid hydrolysis

Currently, the low efficiency and pollution issues associated with biological and chemical methods for the preparation of functional peptides continue to pose challenges, restricting the large-scale production and utilization of functional peptides. This study has found that the ultrasound-assisted organic acid-surfactant system is an efficient and green method for the preparation of functional peptides. The probe ultrasonication-assisted tartaric acid system successfully degraded oat globulins into peptides with a degree of hydrolysis (DH) of 22.8 %. The addition of glyceryl monostearate increased the instantaneous burst rate of the bubble (with a D-value of 16 %), thereby elevating the DH to as high as 36 %. The resulting oat peptide particles exhibited high hydrophobicity, and consequently demonstrated strong foaming capacity (99.6 %), oil holding capacity (399.4 %), emulsifying ability (Emulsifying activity index = 50.5 m2/g, stability index = 108 min), and hydroxyl radical scavenging capacity of 98.9 % (at a concentration of 5 mg/mL), holding great promise for application in the field of food processing. These findings deepen our understanding of the enhanced ultrasonic hydrolysis ability of surfactants and pave a new way to produce functional peptides.

Chemoenzymatic Synthesis of Poly-l-lysine via Esterification with Alcohol in One-Pot

Chemoenzymatic polymerization (CEP) using enzymes as catalysts is gaining attention as an environmentally friendly method for synthesizing polypeptides. This method proceeds under mild conditions in aqueous solvents and leverages the substrate specificity of enzymes, allowing polymerization reactions to occur without the need to protect reactive side-chain functional groups. However, the monomers used must have esterified C-termini, such as amino acids or oligopeptides. In this study, we used l-lysine (Lys-OH) as a model example and performed one-pot CEP with papain without isolating the esterified lysine. Esterification of Lys-OH was achieved by using hydrochloric acid as a catalyst in ethanol, and one-pot polymerization resulted in poly-l-lysine (polyLys) with a peak top degree of polymerization (DP) of 6 and a maximum DP of 18, with a 31% conversion from the nonesterified lysine. The obtained polyLys was all α-linked, demonstrating that regioselective polymerization was successfully achieved even with one-pot CEP.

Chemoenzymatic Polymerization of l-Serine Ethyl Ester in Aqueous Media without Side-Group Protection

Poly(l-serine) (polySer) has tremendous potential as a polypeptide-based functional material due to the utility of the hydroxyl group on its side chain; however, tedious protection/deprotection of the hydroxyl groups is required for its synthesis. In this study, polySer was synthesized by the chemoenzymatic polymerization (CEP) of l-serine ethyl ester (Ser-OEt) or l-serine methyl ester (Ser-OMe) using papain as a catalyst in an aqueous medium. The CEP of Ser-OEt proceeded at basic pH ranging from 7.5 to 9.5 and resulted in the maximum precipitate yield of polySer at an optimized pH of 8.5. A series of peaks detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that the formed precipitate consisted of polySer with a degree of polymerization ranging from 5 to 22. Moreover, infrared spectroscopy, circular dichroism spectroscopy, and synchrotron wide-angle X-ray diffraction measurements indicated that the obtained polySer formed a β-sheet/strand structure. This is the first time the synthesis of polySer was realized by CEP in aqueous solution without protecting the hydroxyl group of the Ser monomer.

Peptide-Based Polyion Complex Vesicles That Deliver Enzymes into Intact Plants To Provide Antibiotic Resistance without Genetic Modification

Direct delivery of enzymes into intact plants using cell-penetrating peptides (CPPs) is an attractive approach for modifying plant functions without genetic modification. However, by conventional methods, it is difficult to maintain the enzyme activity for a long time because of proteolysis of the enzymes under physiological conditions. Here, we developed a novel enzyme delivery system using polyion complex vesicles (PICsomes) to protect the enzyme from proteases. We created PICsome-bearing reactive groups at the surface by mixing an anionic block copolymer, alkyne-TEG-P(Lys-COOH), and a cationic peptide, P(Lys). The PICsome encapsulated neomycin phosphotransferase II (NPTII), a kanamycin resistance enzyme, and protected NPTII from proteases in vitro. A CPP-modified PICsome delivered NPTII into the root hair cells of Arabidopsis thaliana seedlings and provided kanamycin resistance in the seedlings that lasted for 7 days. Thus, the PICsome-mediated enzyme delivery system is a promising method for imparting long-term transient traits to plants without genetic modification.

How to define and study structural proteins as biopolymer materials

Structural proteins, including silk fibroins, play an important role in shaping the skeletons and structures of cells, tissues, and organisms. The amino acid sequences of structural proteins often show characteristic features, such as a repeating tandem motif, that are notably different from those of functional proteins such as enzymes and antibodies. In recent years, materials composed of or containing structural proteins have been studied and developed as biomedical, apparel, and structural materials. This review outlines the definition of structural proteins, methods for characterizing structural proteins as polymeric materials, and potential applications.

Self-assembly and hydrogel formation ability of Fmoc-dipeptides comprising α-methyl-L-phenylalanine

Various biofunctional hydrogel materials can be fabricated in aqueous media through the self-assembly of peptide derivatives, forming supramolecular nanostructures and their three-dimensional networks. In this study, we describe the self-assembly of new Fmoc-dipeptides comprising α-methyl-L-phenylalanine. We found that the position and number of methyl groups introduced onto the α carbons of the Fmoc-dipeptides by α-methyl-L-phenylalanine have a marked influence on the morphology of the supramolecular nanostructure as well as the hydrogel (network) formation ability.

Facile terminal functionalization of peptides by protease-catalyzed chemoenzymatic polymerization toward synthesis of polymeric architectures consisting of peptides

Terminal functionalized polypeptides were synthesized in one-pot chemoenzymatic polymerization using protease for constructing special polymeric architectures.

Poly(alanine-nylon-alanine) as a bioplastic: chemoenzymatic synthesis, thermal properties and biological degradation effects

Poly(amino acids) such as polypeptides and proteins are attractive biomass-based polymers that potentially contribute to circular economy for plastic.