Purification and characterisation of a glutamic acid-containing peptide with calcium-binding capacity from whey protein hydrolysate

Abstract

The bioavailability of dietary ionised calcium is affected by intestinal basic environment. Calcium-binding peptides can form complexes with calcium to improve its absorption and bioavailability. The aim of this study was focused on isolation and characterisation of a calcium-binding peptide from whey protein hydrolysates. Whey protein was hydrolysed using Flavourzyme and Protamex with substrate to enzyme ratio of 25:1 (w/w) at 49 °C for 7 h. The calcium-binding peptide was isolated by DEAE anion-exchange chromatography, Sephadex G-25 gel filtration and reversed phase high-performance liquid chromatography (RP-HPLC). A purified peptide of molecular mass 204 Da with strong calcium binding ability was identified on chromatography/electrospray ionisation (LC/ESI) tandem mass spectrum to be Glu-Gly (EG) after analysis and alignment in database. The calcium binding capacity of EG reached 67·81 μg/mg, and the amount increased by 95% compared with whey protein hydrolysate complex. The UV and infrared spectrometer analysis demonstrated that the principal sites of calcium-binding corresponded to the carboxyl groups and carbonyl groups of glutamic acid. In addition, the amino group and peptide amino are also the related groups in the interaction between EG and calcium ion. Meanwhile, the sequestered calcium percentage experiment has proved that EG-Ca is significantly more stable than CaCl2 in human gastrointestinal tract in vitro. The findings suggest that the purified dipeptide has the potential to be used as ion-binding ingredient in dietary supplements.

Preparation and Evaluation of the Chelating Nanocomposite Fabricated with Marine Algae Schizochytrium sp. Protein Hydrolysate and Calcium

“…After the addition of calcium, changes of the -NH stretching vibration were observed, the red shift from 3410.21 to 3398.41 cm −1 in the amide-A band indicated that the -NH 2 and -NH groups participated in the chelating reaction and that the Ca−N bonds replaced the N−OH (hydrogen bonds). 39 The absorption band of SPH at 1654.36 cm −1 was an amide I band possessing -CO stretching vibrations. It appeared as two peaks (1654.62 and 1647.93 cm −1 ) when combined with calcium, indicating that the carboxylic group involved in the covalent binding reaction with the metal ions.…”

Optimised condition for preparing sea cucumber ovum hydrolysate–calcium complex and its structural analysis

“…Considering nutritional quality and cost, many animal sources, aquatic sources and plant sources are suitable as protein sources to produce protein hydrolysates for calcium‐chelating peptides (Sun et al ., ). Calcium‐chelating peptides have been isolated and characterised from various sources, including cow milk casein (Meisel & Frister, ), whey (Huang et al ., ), tilapia fish muscle and scales (Charoenphun et al ., ; Chen et al ., ) and soy (Lv et al ., ) proteins. Many studies show that the calcium‐chelating activity of protein hydrolysates depends on enzymes types, degree of hydrolysis, amino acid composition, specific groups of amino acids and molecular weight (Liu et al ., ; Guo et al ., ; Sun et al ., ).…”

Desalted Duck Egg White Peptides Promote Calcium Uptake and Modulate Bone Formation in the Retinoic Acid-Induced Bone Loss Rat and Caco-2 Cell Model

“…Additionally, bioactive peptides are suitable candidates as supplements to improve calcium absorption in the gastrointestinal tract of the human body. Currently, calcium-chelating peptides have been isolated and characterized from various sources, including whey [9], alaska pollock backbone and skin [10], shrimp [11], chlorella [12], bovine serum [13], and wheat germ [14]. …”