Mineral-chelating peptides derived from fish collagen: Preparation, bioactivity and bioavailability

Enhancement of Calcium Chelating Activity in Peptides from Sea Cucumber Ovum through Phosphorylation Modification

Recently, phosphorylation has been applied to peptides to enhance their physiological activity, taking advantage of its modification benefits and the extensive study of functional peptides. In this study, water-soluble peptides (WSPs) of sea cucumber ovum were phosphorylated in order to improve the latter's calcium binding capacity and calcium absorption. Enzymatic hydrolysis methods were screened via ultraviolet-visible absorption spectroscopy (UV-Vis), the fluorescence spectrum, and calcium chelating ability. Phosphorylated water-soluble peptides (P-WSPs) were characterized via high-performance liquid chromatography, the circular dichroism spectrum, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, surface hydrophobicity, and fluorescence spectroscopy. The phosphorus content, calcium chelation rate and absorption rate were investigated. The results demonstrated that phosphorylation enhanced the calcium chelating capacity of WSPs, with the highest capacity reaching 0.96 mmol/L. Phosphate ions caused esterification events, and the carboxyl, amino, and phosphate groups of WSPs and P-WSPs interacted with calcium ions to form these bonds. Calcium-chelated phosphorylated water-soluble peptides (P-WSPs-Ca) demonstrated outstanding stability (calcium retention rates > 80%) in gastrointestinal processes. Our study indicates that these chelates have significant potential to develop into calcium supplements with superior efficacy, bioactivity, and stability.

Preparation, characterization, and bioavailability evaluation of antioxidant phosvitin peptide-ferrous complex

BACKGROUND

Iron deficiency anemia (IDA) is one of the commonest global nutritional deficiency diseases, and the low bioavailability of iron is a key contributing factor. The peptide-iron complex could be used as a novel iron supplement to improve iron bioavailability.

RESULTS

In this study, antioxidant low molecular weight (<3 kDa) phosvitin peptide (named PP-4) was separated to prepare a phosvitin peptide-ferrous complex (named PP-4-Fe); then the structural conformation of PP-4-Fe was characterized and its bioavailability by in vitro digestion was evaluated. The results showed that PP-4 had good ferrous-binding activity with 96.14 ± 2.86 μg Fe2+ mg-1 , and had a strong antioxidant effect with 995.61 ± 79.75 μmol TE mg-1 in 2,2'-azinobis'3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 62.3 ± 3.95 μmol FeSO4 mg-1 in ferric ion reducing antioxidant power (FRAP). After ferrous binding, the FRAP activity of PP-4-Fe, enhanced by 1.8 times, formed a more ordered structure with an increase in α-helix and decrease in γ-random coil. The ferrous binding sites of PP-4 involved were the amino, carboxyl, imidazole, and phosphate groups. The PP-4-Fe complex displayed excellent gastrointestinal stability and antioxidant effects during digestion. The iron dialysis percentage of PP-4-Fe was 74.59% ± 0.68%, and increased to 81.10% ± 0.89% with the addition of 0.25 times vitamin C (VC). This indicated that PP-4-Fe displayed excellent bioavailability and VC in sufficient quantities had a synergistic effect on improving bioavailability.

CONCLUSIONS

This study demonstrated that antioxidant phosvitin peptide was an efficient delivery system to protect ferrous ions and suggested that the phosvitin peptide-ferrous complex has strong potential as a ferrous supplement. © 2023 Society of Chemical Industry.

Purification, Characterization, cDNA Cloning, and Bioinformatic Analysis of Zinc-Binding Protein from Magallana hongkongensis

Oysters contain significant amounts of the zinc element, which may also be found in their proteins. In this study, a novel zinc-binding protein was purified from the mantle of the oyster Magallana hongkongensis using two kinds of gel filtration chromatograms. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that its molecular weight was approximately 36 kDa. The protein identified by the Q-Exactive mass spectrometer shared the highest sequence identity with carbonic anhydrase derived from Crassostrea gigas concerning amino acid sequence similarity. Based on homologous cloning and RACE PCR, the full-length cDNA of carbonic anhydrase from Magallana hongkongensis (designated as MhCA) was cloned and sequenced. The cDNA of MhCA encodes a 315-amino-acid protein with 89.74% homology to carbonic anhydrase derived from Crassostrea gigas. Molecular docking revealed that the two zinc ions primarily form coordination bonds with histidine residues in the MhCA protein. These results strongly suggest that MhCA is a novel zinc-binding protein in Magallana hongkongensis.

Phosphorylation modification of bovine bone collagen peptide enhanced its effect on mineralization of MC3T3-E1 cells via improving calcium-binding capacity

This study aimed to investigate the effect of phosphorylation modification of collagen peptide on its calcium-binding capacity and pro-mineralization activity. In this study, collagen peptide (Leu-Thr-Phe, LTF) and phosphorylated LTF (P-LTF) were synthesized and further chelated with calcium ions. The results showed that phosphorylation of LTF significantly enhanced its calcium-binding capacity. Spectra analysis revealed that the calcium-binding sites of P-LTF were mainly carbonyl, carboxyl, and phosphate groups. Molecular docking further demonstrated that the phosphate group introduced by phosphorylation enhanced the calcium-binding capacity of LTF by ionic bonds and coordination bonds. The stability analysis results suggested that intestinal fluid could repair the peptide-calcium complex destroyed by gastric fluid. The cell experiment displayed that P-LTF-Ca significantly improved the mineralization activity of MC3T3-E1 cells, and the order of effective influence was P-LTF-Ca > LTF-Ca > P-LTF > LTF. This study provided the theoretical basis for the potential application of phosphorylation modification in improving bone health.

Comprehensive review: by-products from surimi production and better utilization

Over 1 million MT of surimi is produced globally, which theoretically would generate approximate 2 million MT of solid by-products and more than 1 million MT of wash water. Utilization of the by-products has increasingly become interested based on their nutritional, economical, and environmental issues. Surimi by-products represent an important source of valuable compounds such as functional protein, collagen, gelatin, fish oil, peptides, minerals, and enzymes. Better utilization of the by-products would make the surimi industry sustainable and profitable. This review paper characterizes sources and composition of the solid by-products and wash water generated from the surimi production as well as factors related to extraction and processing techniques. In addition, the potential food applications are explored including specialty foods and snacks, flavor ingredients, bioactive ingredients, and functional ingredients. Moreover, an outlook summarizing the challenges and prospects on the utilization of surimi by-products is provided.

The proximate composition, amino acid profile, fatty acid content, and mineral content of scale flour from three fish species as potential feeds for fish fry

BACKGROUND

Fish scale waste is highly valued both as a functional food ingredient and a potential feed source for farmed fish. This study aimed to analyse the chemical composition, fatty acid profile, and mineral content in fish scale flour of Osphronemus (O) goramy, Cyprinus (C) carpio, and Oreochromis (O) niloticus as potential feed for fish fry.

METHODS

Fish scales were cleaned with 10% w/v NaCl solution at a ratio of 1:10 (w/w) for 24 hours at 4 °C. Agitation was used every eight hours to remove excess protein. Fish scales were evenly arranged in a cooker and cooked at 121 °C for 10 minutes with 15 psi pressure. After cooking, 100 grams of wet fish scales was dried at 50 °C for four hours. Dried fish scales were transformed into flour for proximate composition analysed via standard AOAC method, amino acid and fatty acid assessment employing HPLC and GC-MS, while mineral content was determined using AAS.

RESULTS

The examined fish scale flour from three species displayed significant variations in chemical components, amino acids, and minerals (p<0.01). Crude protein content spanned 49.52% to 72.94%, and fat content ranged from 0.11% to 0.23%. Magnesium levels varied between 767.82 mg/kg and 816.50 mg/kg, calcium content ranged from 3.54 mg/kg to 12.16 mg/kg, iron content was within 40.46 mg/kg to 44.10 mg/kg, and zinc content ranged from 45.80 mg/kg to 139.19 mg/kg. Predominantly, glycine emerged as the main free amino acid (FAA), varying from 13.70% to 16.08%, while histidine had the lowest content, at 0.39% to 0.71%. Conversely, fatty acid content was low in all species examined ranging from 6.73% to 9.48%.

CONCLUSIONS

Flour from three farmed fish types has potential for fish fry feed due to its chemical composition, amino acid, and mineral content. Further validation is needed for amino acid comparison to fish meal.

The proximate composition, amino acid profile, fatty acid content, and mineral content of scale flour from three fish species as potential feeds for fish fry

Background

Fish scale waste is highly valued both as a functional food ingredient and a potential feed source for farmed fish. This study aimed to analyse the chemical composition, fatty acid profile, and mineral content in fish scale flour of Osphronemus (O) goramy, Cyprinus (C) carpio, and Oreochromis (O) niloticus as potential feed for fish fry.

Methods

Fish scales were cleaned with 10% w/v NaCl solution at a ratio of 1:10 (w/w) for 24 hours at 4 °C. Agitation was used every eight hours to remove excess protein. Fish scales were evenly arranged in a cooker and cooked at 121 °C for 10 minutes with 15 psi pressure. After cooking, 100 grams of wet fish scales was dried at 50 °C for four hours. Dried fish scales were transformed into flour for proximate composition analysed via standard AOAC method, amino acid and fatty acid assessment employing HPLC and GC-MS, while mineral content was determined using AAS.

Results

The examined fish scale flour from three species displayed significant variations in chemical components, amino acids, and minerals (p<0.01). Crude protein content spanned 49.52% to 72.94%, and fat content ranged from 0.11% to 0.23%. Magnesium levels varied between 767.82 mg/kg and 816.50 mg/kg, calcium content ranged from 3.54 mg/kg to 12.16 mg/kg, iron content was within 40.46 mg/kg to 44.10 mg/kg, and zinc content ranged from 45.80 mg/kg to 139.19 mg/kg. Predominantly, glycine emerged as the main free amino acid (FAA), varying from 13.70% to 16.08%, while histidine had the lowest content, at 0.39% to 0.71%. Conversely, fatty acid content was low in all species examined ranging from 6.73% to 9.48%.

Conclusions

Flour from three farmed fish types has potential for fish fry feed due to its chemical composition, amino acid, and mineral content. Further validation is needed for amino acid comparison to fish meal.

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, Structural Characterization, and Stability of Low-Molecular-Weight Collagen Peptides-Calcium Chelate Derived from Tuna Bones

This study was conducted to prepare calcium chelate of low-molecular-weight tuna bone collagen peptides (TBCPLMW) with a high chelation rate and to identify its structural characteristics and stability. The optimum conditions for calcium chelation of TBCPLMW (TBCPLMW-Ca) were determined through single-factor experiments and response surface methodology, and the calcium-chelating capacity reached over 90% under the optimal conditions. The amino acid compositions implied that Asp and Glu played important roles in the formation of TBCPLMW-Ca. Structural characterizations determined via spectroscopic analyses revealed that functional groups such as -COO-, N-H, C=O, and C-O were involved in forming TBCPLMW-Ca. The particle size distributions and scanning electron microscopy results revealed that folding and aggregation of peptides were found in the chelate. Stability studies showed that TBCPLMW-Ca was relatively stable under thermal processing and more pronounced changes have been observed in simulated gastric digestion, presumably the acidic environment was the main factor causing the dissociation of the TBCPLMW-Ca. The results of this study provide a scientific basis for the preparation of a novel calcium supplement and is beneficial for comprehensive utilization of tuna bones.

Metal-binding peptides and their potential to enhance the absorption and bioavailability of minerals

Minerals including calcium, iron, zinc, magnesium, and copper have several human nutritional functions due to their metabolic activities. Body tissues require sufficient levels of a variety of micronutrients to maintain their health. To achieve these micronutrient needs, dietary consumption must be adequate. Dietary proteins may regulate the biological functions of the body in addition to acting as nutrients. Some peptides encoded in the native protein sequences are primarily responsible for the absorption and bioavailability of minerals in physiological functions. Metal-binding peptides (MBPs) were discovered as potential agents for mineral supplements. Nevertheless, sufficient studies on how MBPs affect the biological functions of minerals are lacking. The hypothesis is that the absorption and bioavailability of minerals are significantly influenced by peptides, and these properties are further enhanced by the configuration and attribute of the metal-peptide complex. In this review, the production of MBPs is discussed using various key parameters such as the protein sources and amino acid residues, enzymatic hydrolysis, purification, sequencing and synthesis and in silico analysis of MBPs. The mechanisms of metal-peptide complexes as functional food ingredients are elucidated, including metal-peptide ratio, precursors and ligands, complexation reaction, absorbability and bioavailability. Finally, the characteristics and application of different metal-peptide complexes are also described.

Marine Collagen: A Promising Biomaterial for Wound Healing, Skin Anti-Aging, and Bone Regeneration

Marine organisms harbor numerous bioactive substances that can be utilized in the pharmaceutical and cosmetic industries. Scientific research on various applications of collagen extracted from these organisms has become increasingly prevalent. Marine collagen can be used as a biomaterial because it is water soluble, metabolically compatible, and highly accessible. Upon review of the literature, it is evident that marine collagen is a versatile compound capable of healing skin injuries of varying severity, as well as delaying the natural human aging process. From in vitro to in vivo experiments, collagen has demonstrated its ability to invoke keratinocyte and fibroblast migration as well as vascularization of the skin. Additionally, marine collagen and derivatives have proven beneficial and useful for both osteoporosis and osteoarthritis prevention and treatment. Other bone-related diseases may also be targeted by collagen, as it is capable of increasing bone mineral density, mineral deposition, and importantly, osteoblast maturation and proliferation. In this review, we demonstrate the advantages of marine collagen over land animal sources and the biomedical applications of marine collagen related to bone and skin damage. Finally, some limitations of marine collagen are briefly discussed.

Bioactive peptides from foods: production, function, and application

Bioactive peptides are a class of peptides with special physiological functions and have potential applications in human health and disease prevention. Bioactive peptides have gained much research attention because they affect the cardiovascular, endocrine, immune, and nervous systems. Recent research has reported that bioactive peptides are of great value for physiological function regulation, including antioxidation, anti-hypertension, antithrombosis, antibacterial properties, anti-cancer, anti-inflammation, anti-diabetic, anti-obesity, cholesterol-lowering, immunoregulation, mineral binding and opioid activities. The production of food-derived bioactive peptides is mainly through the hydrolysis of digestive enzymes and proteolytic enzymes or microbial fermentation. The purpose of this review is to introduce the production, function, application, challenges, and prospects of food-derived bioactive peptides.

Exploring Molecular Insights of Cereal Peptidic Antioxidants in Metabolic Syndrome Prevention

The prevalence of metabolic syndrome (MetS) is presently an alarming public health problem globally. Oxidative stress has been postulated to be strongly correlated with MetS, such as type 2 diabetes, obesity, hypertension, cardiovascular diseases, and certain cancers. Cereals are important staple foods which account for a huge proportion of the human diet. However, owing to recent growing demand and the search for natural antioxidants for the prevention and management of MetS, cereal peptides have gained increasing attention for developing functional ingredients or foods with substantial antioxidant properties. This review explores the current production techniques for cereal peptidic antioxidants and their potential mechanism of action in the prevention and management of MetS.