Purification of a histidine-containing peptide with calcium binding activity from shrimp processing byproducts hydrolysate

The shrimp processing byproducts were hydrolyzed by various proteases, and calcium binding activity of the hydrolysates was examined. Among the digests, trypsin digest showed the most potent calcium binding activity (0.294 mmol/g-protein) and highest degree of hydrolysis (18.4%). The trypsin hydrolysate was fractionated according to the molecular weights using ultrafiltration membrane system. The lowest molecular weight fraction (< 1 kDa) showed the highest calcium binding activity. Then, the lowest molecular weight fraction was isolated and purified by ion-exchange chromatography, gel filtration, and ODS reversed high-performance liquid chromatography. The purified peptide showed the highest calcium binding activity of 2.70 mmol/g-protein, and its structure was identified as Thr-Cys-His by ESI/MS/MS. Therefore, these results suggested that the peptide derived from shrimp processing byproducts protein hydrolysates is responsible for higher calcium binding properties and may be as natural functional additive in food industry.