Preparation and structure characterization of soluble bone collagen peptide chelating calcium
In this study, G-25 gel chromatography, X-diffraction, scanning electron microscopy (SEM), UV and Fourier transform infrared spectroscopy (FTIR) were used to analyze soluble collagen peptides chelating calcium. Collagen peptide hydrolysis can be divided into four components using G-25 gel chromatography. Each component of calcium binding capacity was different and the components whose molecular weight was less than 5000 Da had a relatively high calcium binding capacity. In the infrared spectra experimental certification, after the collagen peptides had combined with calcium, amide I, II wave number was displaced, which indicated that amino nitrogen atoms and oxygen atoms on the carboxyl groups were involved in chelation. In the UV scan spectra, the characteristic absorption peak of the collagen peptide’s carbonyl and the peptide bond was clearly shifted, indicating that collagen peptides have reacted with calcium. In SEM spectra, a lot of white grains were seen to be "embedded" clearly in the surface of the collagen peptide, indicating that besides the reaction of coordination between collagen peptides and calcium, there was a certain degree of adsorption. After combination with calcium, the X-ray diffraction spectra showed that the no rules non-crystal structure collagen peptides turned into rules crystal structure. According to the structure analysis which showed that collagen peptide chelated calcium is a five-membered ring structure, calcium is in the center and was combined strongly with both the amino- and carboxyl-group.
Key words: Bone, calcium binding, molecular weight, collagen peptide.