Isolation of a calcium-binding peptide from bovine serum protein hydrolysates

A calcium-binding peptide was isolated from the hydrolysates of bovine serum protein (BSP). BSP was hydrolyzed using 3 different types of proteases, Alcalase, Flavourzyme, and Protamex, and the degree of hydrolysis was determined and monitored using trinitrobenzenesulfonic acid and SDS-PAGE. The hydrolysates of BSP using Alcalase were selected and ultra-filtered below 3 kDa. The membrane-filtered solution was then fractionated using ion exchange chromatography and normal phase HPLC to isolate a calcium-binding peptide. The calcium-binding capacity was determined by the orthophenanthroline method. The sequence of the purified calcium-binding peptide was analyzed using LC/electron spray ionization (LC/ESI)-tandem mass spectroscopy and identified to be Asp-Asn-Leu-Pro-Asn-Pro-Glu-Asp-Arg-Lys-Asn-Tyr-Glu, which has a molecular weight of 1,603 Da.