Soybean peptide aggregates improved calcium binding capacity

• Aggregation of soybean peptides played an important role in calcium binding.
• The calcium binding capacity would drop after degeneration agents addition.
• The removal of degeneration agents resulted in peptide reaggregation and recovery of the calcium binding capacity.

Soybean peptides are believed to have calcium binding sites as Asp and Glu on side chains. However, the effects of peptide aggregation on calcium binding capacity remain unknown. Peptides with different calcium binding capacities (F1 and F2) were separated in this study by calcium immobilized metal affinity chromatography. The calcium binding capacities and apparent molecular weight distributions of F1 and F2 were analyzed before and after the denaturation agents removal. Results showed that F2 with higher calcium binding capacity was more prone to aggregate than F1. The calcium binding capacity of both F1 and F2 decreased after urea or urea and 0.5% SDS treatments. The removal of denaturation agents resulted in peptide reaggregation and recovery of the calcium binding capacity of F2; no significant changes were found for F1. All the findings implied that aggregation of soybean peptides played an important role in calcium binding.