Preparation and Characterization of a Novel Peptide Chelating Calcium from Bovine Bone Hydrolysates

In order to utilize bovine bone byproducts in a calcium supplement with high solubility, bovine bone was hydrolyzed by a specific bone-degrading collagenolytic protease extracted from Bacillus cereus MBL13 (isolated from chopped animal bone wastes). A calcium-binding bovine bone peptide (BBP) was successfully purified from the bone hydrolysate. Its amino acid sequence was identified as Phe-Glu-Ser-Asn-Phe-Asn-Thr-Gln-Ala-Thr-Asn-Arg (MW 1428 Da) through ESI-QTOF tandem mass analysis. The chemical and structural properties of the BBP chelating calcium (BBP-Ca) were investigated. The results proved that BBP-Ca was rich in peptide and calcium, and exhibited excellent thermal solubility and high solubility under either acidic or basic conditions, which were beneficial to be absorbed and transported in the gastrointestinal tracts of humans. Analysis of ultraviolet spectroscopy, fluorescence spectroscopy and Fourier transform infrared spectroscopy suggested that carboxyl groups, amino groups, and carbonyl groups of BBP were the primary chelating calcium sites. Raman spectroscopy showed that the secondary structure of BBP-Ca mainly contained beta-folding and random coil. Meanwhile, X-ray diffraction spectra demonstrated that the irregular non-crystal structure of BBP turned into the crystal structure after chelated with calcium. Moreover, SEM indicated that there was a certain degree of adsorption besides the coordinate binding and ion binding between BBP and calcium. Therefore, BBP-Ca was a new and stable peptide-calcium chelate by the analysis of its chemical and structural properties. This research provides a theoretical basis for the development of new calcium nutraceutical additives.