Identification of novel calcium-absorption promoting peptides from lactopontin gastrointestinal digests and investigation of their intestinal calcium transport mechanism.
This study clarifies L-OPN peptide's core calcium absorption mechanism, providing a scientific basis for understanding L-OPN's biological role and developing infant nutritional products.
Abstract
Lactopontin (L-OPN), a milk-derived active protein vital for the growth of infants and young children, was studied for the calcium absorption-promoting activity and mechanism of its gastrointestinal digestive products. An in vitro dynamic infant digestive system simulated L-OPN digestion; the products were separated via desalting, ultrafiltration and HPLC to screen high calcium-chelating peptides. MS analysis revealed dominant low-molecular-weight peptides with acidic amino acids and serine phosphorylation. Molecular docking identified four high-affinity peptides: SELS(+79.97)KELTPK, KLS(+79.97)QEFH, HSDESDEVDF, PTDIPTIA, with Glu and Asp as key Ca2+-binding residues. In the Caco-2 model, their calcium transport rose by 83.55%, 95.44%, 71.53% and 81.62% vs. CaCl2 group, with lower intracellular calcium retention (accelerated Ca2+ efflux). MS confirmed KLS(+79.97)QEFH's intact intestinal absorption via stable calcium-chelating structure. This study clarifies L-OPN peptide's core calcium absorption mechanism, providing a scientific basis for understanding L-OPN's biological role and developing infant nutritional products.
Conventional calcium supplements often show limited bioaccessibility and suboptimal gastrointestinal tolerance. Food-derived proteins, protein hydrolysates, and peptide–calcium chelates have been investigated as protein-based calcium chelates. This review organizes these systems along a structural continuum from proteins to hydrolysates and peptide–calcium chelates, in which enzymatic hydrolysis, fractionation, purification, and chelation reshape carrier composition, molecular weight distribution, and calcium coordination characteristics. Within this framework, this review examines the preparation strategies, molecular features, gastrointestinal stability, intestinal transport behavior, and bone-related functions of protein-based calcium chelates. Particular attention is given to the effects of chelate type, molecular weight distribution, peptide sequence, and coordination stability on calcium retention, solubility, and transport-related behavior during digestion, as well as their links with osteogenic responses, gut microbiota changes, and the gut–bone axis. Overall, this review provides a structured framework for evaluating food-derived protein-based calcium chelates and their potential application in food-based calcium delivery systems, while highlighting future needs in functional validation, product standardization, safety assessment, and clinically relevant evidence.
Tingting Li, Yaxiong Gao, Qiang Zhou et al.· Frontiers in Nutrition· 0 citations
This study aimed to address the poor bioavailability of traditional calcium supplements by investigating the Moringa oleifera Lam. leaf-derived peptide KTFQGPPHG and its peptide-calcium chelate. Virtual screening predicted potential interactions of KTFQGPPHG with Ca2+ and calcium transport-related proteins, including TRPV6, Cav1.3, and PepT1. During simulated digestion, KTFQGPPHG-Ca showed high intestinal-phase stability, with a calcium retention rate of 94.13 ± 1.47%, while its major digestive fragment, TFQGPPHG, retained substantial calcium-binding activity. In Caco-2 cell monolayers, both KTFQGPPHG-Ca and TFQGPPHG-Ca significantly enhanced calcium transport compared with CaCl2, with Cav1.3 and TRPV6 being major pathways involved in this process. Proteomic analysis suggested that these chelates may regulate calcium absorption-associated epithelial pathways, including “cell adhesion molecules” and “ECM–receptor interaction,” which may contribute to epithelial barrier integrity and cell-matrix signaling associated with Ca2+ transport. In conclusion, KTFQGPPHG-Ca exhibits high gastrointestinal stability and enhances calcium transport through multiple pathways, supporting its potential development as a novel calcium supplement.
Zi-Lin Wang, Ruijing Gu, Yu Zhou et al.· Journal of Agricultural and...· 0 citations
This study developed a novel peptide-calcium chelate (SPH-Ca) from Spirulina platensis hydrolysates with the aim of improving peptide stability and enhancing lipid-lowering activity. The chelation process was optimized by response surface methodology, yielding a calcium binding capacity of 52.9% under the optimal conditions of 60.1 °C, 40.4 min, and pH 5.1. Structural analyses using FT-IR and XRD confirmed the successful coordination of calcium ions with carboxyl and amino groups in peptides, forming a stable complex. SPH-Ca exhibited potent pancreatic lipase inhibitory activity with an IC50 of 2.02 mg/mL and functioned via a non-competitive inhibition mechanism (Ki = 0.82 mM). Notably, it retained 68.7% of its inhibitory activity after in vitro simulated gastrointestinal digestion, demonstrating significantly improved stability. In a high-fat diet-induced Caenorhabditis elegans model, SPH-Ca treatment reduced triglyceride levels by up to 75% (from 0.756 mmol/gprot in the model group to 0.195 mmol/gprot) and total cholesterol by up to 55% (from 0.795 mmol/gprot to 0.350 mmol/gprot), with 100% survival rate confirming the absence of toxicity. Further mechanistic studies in C. elegans revealed that the lipid-lowering effect was mediated through activation of the AMPK signaling pathway and modulation of gut microbiota, particularly an enrichment of Paracoccus marcusii. These findings highlight SPH-Ca as a stable and effective lipid-lowering agent with potential for further development.
Qiaohui Zeng, Zhiqi Xie, Miaoluan Lin et al.· International Journal of Bio...· 0 citations
Chalaza (CLZ), a byproduct generated during egg processing, has shown potential to promote calcium absorption, but its underlying mechanisms remain unclear. In a low-calcium growing rat model, coadministration of CLZ with CaCO3 dose-dependently increased apparent calcium absorption and retention, enhanced bone calcium deposition, and improved bone microarchitecture and mechanical properties compared with CaCO3 alone. These effects were accompanied by improved duodenal morphology, upregulation of intestinal calcium transport-related proteins (TRPV6, PMCA1b, and S100G/CaBP-D9k), and associated gut microbiota and SCFA changes. Representative digestion-derived peptides were synthesized and showed calcium-chelating capacity, inhibition of calcium phosphate crystallization, gastrointestinal calcium release, and thermal stability, supporting their role as exploratory calcium-binding candidates. Overall, this study supports the potential application of the high-value utilization of egg byproducts and the development of efficient calcium supplementation strategies.
Shenwan Wang, Ye Qi, Qimeng Zhou et al.· Journal of Agricultural and...· 0 citations
Across both in vitro and in vivo models, ultra-low molecular weight collagen (LMWCP), with more than 45% di- and tripeptides, exhibited faster early-phase absorption kinetics, thereby enhancing early-phase bioavailability.
Reyhan Nergiz-Unal, Stephan Dierckx, C. Roye et al.· PeerJ· 0 citations
Antioxidant peptides derived from crocodile blood remain poorly characterized, regarding defined sequences, gastrointestinal stability, intestinal transport, and allergenicity. In this study, antioxidant peptides were generated from crocodile (Crocodylus siamensis) blood proteins via enzymatic hydrolysis. Two peptides (MLHVGPEIAPL and AAHYPKDFGL), prepared by pepsin, exhibited strong antioxidant activity, with 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity of 10.39-14.09 μmol Trolox equivalents (TE)/mg and reducing power of 2.43-5.00 μmol TE/mg. Simulated gastrointestinal digestion revealed that AAHYPKDFGL was further hydrolyzed into shorter peptides (AAHYPK and DFGL) with retained activity. These peptides could pass the Caco-2 monolayer with apparent permeability coefficients of 2.80-11.98 × 10-7 cm/s, despite being degraded by aminopeptidase N to varying degrees. They reduced cellular oxidative stress (decreased superoxide/malondialdehyde levels) without affecting major antioxidant enzymes. No significant allergenicity was detected for these peptides. These findings highlighted crocodile blood proteins as an underexplored source of antioxidant peptides for functional food application.
Zhiying Wang, Yugui Wang, Hui Hong et al.· Food Chemistry· 0 citations
