Preparation and characterization of aminoethyl hydroxypropyl starch modified with collagen peptide

Transglutaminase in Foods and Biotechnology

Stabilization and reusability of enzyme transglutaminase (TGM) are important goals for the enzymatic process since immobilizing TGM plays an important role in different technologies and industries. TGM can be used in many applications. In the food industry, it plays a role as a protein-modifying enzyme, while, in biotechnology and pharmaceutical applications, it is used in mediated bioconjugation due to its extraordinary crosslinking ability. TGMs (EC 2.3.2.13) are enzymes that catalyze the formation of a covalent bond between a free amino group of protein-bound or peptide-bound lysine, which acts as an acyl acceptor, and the γ-carboxamide group of protein-bound or peptide-bound glutamine, which acts as an acyl donor. This results in the modification of proteins through either intramolecular or intermolecular crosslinking, which improves the use of the respective proteins significantly.

Water-soluble chlorin e6-hydroxypropyl chitosan as a high-efficiency photoantimicrobial agent against Staphylococcus aureus

The development of new antimicrobial agents is important to combat infections caused by pathogenic bacteria. Herein, Hydroxypropyl chitosan (HPCS), a hydrophilic modified product of chitosan (CS), was employed as a carrier of the photosensitizer chlorin e6 (Ce6) through an amide bond to obtain the products (HPCS-Ce6 conjugates) with a degree of substitution (DS) ranging from 2.95% to 5.25%. The UV-vis absorption spectra and 1H NMR spectra confirmed the successful synthesis of the products. The products have a better and more stable reactive oxygen species (ROS) generation capacity and higher bacterial affinity than Ce6. At a very low dose (1.8 μg/mL), the highest DS product (HPCS-Ce6-3) can effectively kill Staphylococcus aureus (S. aureus) under 660 nm irradiation. In addition, the HPCS-Ce6 conjugates showed high biocompatibility in the CCK-8 test. The HPCS-Ce6 conjugates could be a photodynamic antibacterial agent with good water solubility, high biocompatibility, and antibacterial activity.

Effects of ion concentrations on the hydroxyl radical scavenging rate and reducing power of fish collagen peptides

Empirical evidence proves that the antioxidant property plays a main role in the biological activities of biomaterials, which is influenced by several factors. In order to explore in-depth, the influence of ionic systems on the antioxidant activity of collagen peptides was studied. Type-I-collagen peptides (GBB-10SP and TYPE-S) contained a high amount of hydrophobic amino acids and possessed good antioxidant activity at high concentrations in water. On the other hand, increasing [H⁺ ] and [Na⁺ ] concentrations (0.1 M to 0.5 M) decreased the reducing power of GBB-10SP and TYPE-S; however, [Ca²⁺ ] had no effect on the reducing power. Interestingly, the hydroxyl radical scavenging rate of these two peptides was increased by [Na⁺ ], decreased by [H⁺ ], and [Ca²⁺ ] had no effect. In general, TYPE-S showed better antioxidant properties than GBB-10SP. Overall, the above results confirmed that the antioxidant capacity of collagen peptides was affected by [H⁺ ] and [Na⁺ ] and not by [Ca²⁺ ]. PRACTICAL APPLICATIONS: The present study mainly deals with the influence of ions on the antioxidant properties of collagen peptides. Recently, fish collagen peptides have been widely used as food supplements to cure several disorders and maintain normal physiological health in humans. It is noted that the use of collagen from fish processing wastes has brought several potential benefits including low value-added products, preventing environmental pollution, and disease transmission by mammalian-based collagen. But the biological activity of this peptide varied based on the preparation and its biochemical compositions. Here, we are reporting how to improve the biological activity of collagen, and also the factors affecting the antioxidant properties in order to avoid the down-regulating mechanism. This study concluded that the [H⁺ ] and [Na⁺ ] influenced the antioxidant properties of collagen peptides, but [Ca²⁺ ] had not effect on the antioxidant properties.