A novel calcium-chelating peptide purified from Auxis thazard protien hydrolysate and its binding properties with calcium

Abstract

Auxis thazard protein peptides were prepared by enzymatic hydrolysis and membrane separation and then sequentially purified with Sephadex G-15 gel chromatography and reversed phase high performance liquid chromatography (RP-HPLC) based on their calcium binding capacity. A novel peptide purified from Auxis thazard protien peptides exhibited the highest calcium binding activity (76.8 ± 4.5 mg/g) and was identified as Glu-Pro-Ala-His (MW = 453.3 Da). The results of FTIR and mass spectrometry showed that the binding sites of calcium-binding peptide involved the carboxylic group of Glu, as well as the carboxylic group and the amino group of His. A hypothesized molecular model of peptide-calcium chelate was constructed and the difference of the molecular structure and apparent structure of peptide (Glu-Pro-Ala-His) before and after chelating with calcium was also confirmed by scanning electron microscope. These study results indicated that Auxis thazard protein hydrolysate was a high quality source of peptides with calcium binding activity.

Keywords

• Auxis thazard protien hydrolysate
• Calcium-binding peptide
• Calcium binding properties
• Molecular model of peptide-calcium chelate