Characteristics and osteogenic mechanism of glycosylated peptides-calcium chelate

Biomimetic Bone-Like Composite Hydrogel Scaffolds Composed of Collagen Fibrils and Natural Hydroxyapatite for Promoting Bone Repair

Bone is a complex organic-inorganic composite tissue composed of ∼30% organics and ∼70% hydroxyapatite (HAp). Inspired by this, we used 30% collagen and 70% HAp extracted from natural bone using the calcination method to generate a biomimetic bone composite hydrogel scaffold (BBCHS). In one respect, BBCHS, with a fixed proportion of inorganic and organic components similar to natural bone, exhibits good physical properties. In another respect, the highly biologically active and biocompatible HAp from natural bone effectively promotes osteogenic differentiation, and type I collagen facilitates cell adhesion and spreading. Additionally, the well-structured porosity of the BBCHS provides sufficient growth space for bone marrow mesenchymal stem cells (BMSCs) while promoting substance exchange. Compared to the control group, the new bone surface of the defective location in the B-HA70+Col group is increased by 3.4-fold after 8 weeks of in vivo experiments. This strategy enables the BBCHS to closely imitate the chemical makeup and physical structure of natural bone. With its robust biocompatibility and osteogenic activity, the BBCHS can be easily adapted for a wide range of bone repair applications and offers promising potential for future research and development.

Preparation, characterization, and property evaluation of Hericium erinaceus peptide-calcium chelate

Recently, owing to the good calcium bioavailability, peptide-calcium chelates made of various foods have been emerging. Hericium erinaceus, an edible fungus, is rich in proteins with a high proportion of calcium-binding amino acids. Thus, mushrooms serve as a good source to prepare peptide-calcium chelates. Herein, the conditions for hydrolyzing Hericium erinaceus peptides (HP) with a good calcium-binding rate (CBR) were investigated, followed by the optimization of HP-calcium chelate (HP-Ca) preparation. Furthermore, the structure of the new chelates was characterized along with the evaluation of gastrointestinal stability and calcium absorption. Papain and a hydrolysis time of 2 h were selected for preparing Hericium erinaceus peptides, and the conditions (pH 8.5, temperature 55°C, time 40 min, and mass ratio of peptide/CaCl2 4:1) were optimal to prepare HP-Ca. Under this condition, the chelates contained 6.79 ± 0.13% of calcium. The morphology and energy disperse spectroscopy (EDS) analysis showed that HP-Ca was loose and porous, with an obvious calcium element signal. The ultraviolet-visible (UV) absorption and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that calcium possibly chelates to HP via interaction with free -COO- from acidic amino acids and C = O from amide. HP-Ca displayed good stability against stimulated gastrointestinal digestion. Moreover, HP-Ca significantly improved the calcium absorption by Caco-2 epithelial cells. Thus, HP-Ca is a promising Ca supplement with high calcium bioavailability.

Talin mechanotransduction in disease

Talin protein (Talin 1/2) is a mechanosensitive cytoskeleton protein. The unique structure of the Talin plays a vital role in transmitting mechanical forces. Talin proteins connect the extracellular matrix to the cytoskeleton by linking to integrins and actin, thereby mediating the conversion of mechanical signals into biochemical signals and influencing disease progression as potential diagnostic indicators, therapeutic targets, and prognostic indicators of various diseases. Most studies in recent years have confirmed that mechanical forces also have a crucial role in the development of disease, and Talin has been found to play a role in several diseases. Still, more studies need to be done on how Talin is involved in mechanical signaling in disease. This review focuses on the mechanical signaling of Talin in disease, aiming to summarize the mechanisms by which Talin plays a role in disease and to provide references for further studies.

A critical review of a typical research system for food-derived metal-chelating peptides: Production, characterization, identification, digestion, and absorption

In the past decade, food-derived metal-chelating peptides (MCPs) have attracted significant attention from researchers working towards the prevention of metal (viz., iron, zinc, and calcium) deficiency phenomenon by primarily inhibiting the precipitation of metals caused by the gastrointestinal environment and exogenous substances (including phytic and oxalic acids). However, for the improvement of limits of current knowledge foundations and future investigation directions of MCP or their derivatives, several review categories should be improved and emphasized. The species' uniqueness and differences in MCP productions highly contribute to the different values of chelating ability with particular metal ions, whereas comprehensive reviews of chelation characterization determined by various kinds of technique support different horizons for explaining the chelation and offer options for the selection of characterization methods. The reviews of chelation mechanism clearly demonstrate the involvement of potential groups and atoms in chelating metal ions. The discussions of digestive stability and absorption in various kinds of absorption model in vitro and in vivo as well as the theory of involved cellular absorption channels and pathways are systematically reviewed and highlighted compared with previous reports as well. Meanwhile, the chelation mechanism on the molecular docking level, the binding mechanism in amino acid identification level, the utilizations of everted rat gut sac model for absorption, and the involvement of cellular absorption channels and pathway are strongly recommended as novelty in this review. This review makes a novel contribution to the literature by the comprehensive prospects for the research and development of food-derived mineral supplements.

Novel Ca-Chelating Peptides from Protein Hydrolysate of Antarctic Krill (Euphausia superba): Preparation, Characterization, and Calcium Absorption Efficiency in Caco-2 Cell Monolayer Model

Antarctic krill (Euphausia superba) is the world's largest resource of animal proteins and is thought to be a high-quality resource for future marine healthy foods and functional products. Therefore, Antarctic krill was degreased and separately hydrolyzed using flavourzyme, pepsin, papain, and alcalase. Protein hydrolysate (AKH) of Antarctic krill prepared by trypsin showed the highest Ca-chelating rate under the optimized chelating conditions: a pH of 8.0, reaction time of 50 min, temperature of 50 °C, and material/calcium ratio of 1:15. Subsequently, fourteen Ca-chelating peptides were isolated from APK by ultrafiltration and a series of chromatographic methods and identified as AK, EAR, AEA, VERG, VAS, GPK, SP, GPKG, APRGH, GVPG, LEPGP, LEKGA, FPPGR, and GEPG with molecular weights of 217.27, 374.40, 289.29, 459.50, 275.30, 300.36, 202.21, 357.41, 536.59, 328.37, 511.58, 516.60, 572.66, and 358.35 Da, respectively. Among fourteen Ca-chelating peptides, VERG presented the highest Ca-chelating ability. Ultraviolet spectrum (UV), Fourier Transform Infrared (FTIR), and scanning electron microscope (SEM) analysis indicated that the VERG-Ca chelate had a dense granular structure because the N-H, C=O and -COOH groups of VERG combined with Ca2+. Moreover, the VERG-Ca chelate is stable in gastrointestinal digestion and can significantly improve Ca transport in Caco-2 cell monolayer experiments, but phytate could significantly reduce the absorption of Ca derived from the VERG-Ca chelate. Therefore, Ca-chelating peptides from protein hydrolysate of Antarctic krill possess the potential to serve as a Ca supplement in developing healthy foods.

Preparation of a cattle bone collagen peptide-calcium chelate by the ultrasound method and its structural characterization, stability analysis, and bioactivity on MC3T3-E1 cells

This study was designed to prepare a cattle bone-derived collagen peptide-calcium chelate by the ultrasound method (CP-Ca-US), and its structure, stability, and bioactivity on MC3T3-E1 cells were characterized. Single-factor experiments optimized the preparation conditions: ultrasound power 90 W, ultrasound time 40 min, CaCl₂/peptides ratio 1/2, pH 7. Under these conditions, the calcium-chelating ability reached 39.48 μg mg^-1. The result of Fourier transform-infrared spectroscopy indicated that carboxyl oxygen and amino nitrogen atoms were chelation sites. Morphological analysis indicated that CP-Ca-US was characterized by a porous surface and large particles. Stability analysis demonstrated that CP-Ca-US was stable in the thermal environment and under intestinal digestion. CP-Ca-US showed more stability in gastric juice than the chelate prepared by the hydrothermal method. Cell experiments indicated that CP-Ca-US increased osteoblast proliferation (proliferation rate 153% at a concentration of 300 μg mL^-1) and altered the cell cycle. Significantly, CP-Ca-US enhanced calcium absorption by interacting with calcium-sensing receptors and promoted the mineralization of MC3T3-E1 cells. This study provides the scientific basis for applying the ultrasound method to prepare peptide-calcium chelates and clarifies the positive role of chelates in bone building.