Generation of a baby clam (Corbiculidae sp.) meat protein hydrolysate with calcium-binding activity, evaluation of its characteristics, and identification of a novel calcium-binding hexapeptide (LPLTII) applicable as a calcium chelator

Abstract

Our research focused on generating a protein hydrolysate from baby clam (Corbiculidae sp.) meat. The resulting product had a hydrolysis degree (DH) of 85.54 ± 2.25 % and demonstrated a calcium-binding capacity (CaBC) of 1085.82 ± 10.41 μg Ca²⁺/g protein. A comprehensive analysis of the hydrolysate was conducted, examining its amino acid profile, functional properties (including solubility, heat resistance, foaming and emulsifying capabilities, and liquid retention characteristics), and bioactivity stability across various pH levels and temperatures. The hydrolysate was then fractionated using centrifugal devices with membranes of different molecular weight cut-offs (30, 10, 3, and 1 kDa). Among the five resulting peptide fractions, the <1 kDa fraction showed the highest CaBC at 4594.87 ± 61.31 μg Ca²⁺/g protein. This fraction underwent tandem mass spectrometry for peptide sequencing. The analysis identified a calcium-binding peptide (668.45 Da) and its amino acid sequence of Leucine-Proline-Leucine-Threonine-Isoleucine-Isoleucine (LPLTII). In silico methods suggested this peptide is neither toxic nor allergenic. Molecular docking simulations indicated that Thr₄ and Leu₃ are the primary calcium-binding sites on the peptide. The calcium binding hydrolysate and its fractions could be used as calcium binders, added in functional food or nutraceutical. Besides, they could be fortified into food products to enrich required amino acids. They could be used for food quality enhancement as well.