In vitrodigestion profile and calcium absorption studies of a sea cucumber ovum derived heptapeptide–calcium complex

Abstract

In this study, a novel calcium-binding heptapeptide (NDEELNK) that is released during the trypsin hydrolysis of sea cucumber ovum was identified by peptidomics. The calcium binding mode, in vitro digestion profile and calcium absorption of the NDEELNK-calcium complex were investigated. The NDEELNK peptide could spontaneously bind calcium with a 1 : 1 stoichiometry, and the calcium-binding site might involve the carboxyl oxygen and amino nitrogen atoms of two glutamic acid and one aspartic acid residues in the NDEELNK peptide. The NDEELNK-calcium complex underwent disaggregation and self-aggregation in a mesh of smaller size during simulated gastrointestinal digestion, clarified by dynamic light scattering and confocal laser-scanning microscopy. In addition, the NDEELNK-calcium complex could be conducive to calcium absorption across Caco-2 cell monolayers. The findings from this research suggest possible utilization of hydrolyzed peptides from sea cucumber ovum as dietary supplements to improve calcium absorption.

In vivo mechanism of action of matrix metalloprotease (MMP) in the autolysis of sea cucumber (Stichopus japonicus)

“…The distribution of free Ca 2+ in SCBW was monitored by Fluo‐3 AM and CLSM (Figure ). The fluorescent probe Fluo‐3 AM can bind free Ca 2+ and then emits green fluorescence at emission wavelength from 510 to 525 nm (Cui et al, ). Our results showed that the fluorescence intensity from free Ca 2+ in blank solution treated SCBW increased first and reached a maximum value at 4 hr following the treatment, but decreased thereafter (Figure A–D,I).…”

“…The level of free Ca 2+ in SCBW was visualized in situ using CLSM. This probe, fluo‐3 a.m., was shown to be highly sensitive fluorescence probe for free Ca 2+ (Cui et al, ). The 6‐μm‐thick transverse sections of SCBW were cut by a cryostat microtome and incubated in 100 μM of fluorescent calcium indicator dyes (Fluo‐3 a.m.) for 30 min at 24 ± 1°C.…”

Production, Purification, and Potential Health Applications of Edible Seeds’ Bioactive Peptides: A Concise Review

“…Due to the excessive cost of AAs, peptides derived from edible seed proteins commonly produced in vivo or in vitro by enzymatic proteolysis are promising ligands for complexation with divalent metals towards improving mineral bioavailability and for alleviating micronutrient deficiency [130,133,134]. To date, a variety of metal-chelating peptides have been generated and identified from different edible seed proteins [135,136]. For instance, Wang et al [137] reported that a pentapeptide FVDVT from wheat germ protein hydrolysate (WGPH) possessed significantly (86%) higher calcium-binding property when compared to crude hydrolysates.…”

Peptide–Mineral Complexes: Understanding Their Chemical Interactions, Bioavailability, and Potential Application in Mitigating Micronutrient Deficiency

“…As shown in Table 2 , the markers of calcium, iron, and zinc bioavailability were improved when preformed peptide–mineral complexes were used. For instance, calcium absorption was significantly increased in Caco-2 when complexed with NDEELNK and sea cucumber ovum hydrolysate [ 21 ]. Caetano-Silva et al [ 77 ] also observed ferritin synthesis, resulting in a 70% increase in iron uptake when Caco-2 cells were treated with iron complexes with low-molecular weight (<5 kDa) peptides.…”

“…The mineral-chelating properties of peptides are attributed to the structural diversity of their backbone, which contains both the terminal carboxyl and amino groups, and the side chains of amino acid residues [ 5 , 9 ]. To date, a variety of metal-chelating peptides has been generated and identified from different food sources, such as milk, egg, soybean and sea cucumber [ 21 , 22 , 23 , 24 ]. Regardless, caseinophosphopeptides (CPPs) are the most extensively studied mineral-chelating peptides that have been successfully applied as food ingredients for mitigating mineral deficiency [ 20 ].…”