Enzymatically synthesized γ-[Glu](n≥1)-Gln as novel calcium-binding peptides to deliver calcium with enhanced bioavailability

摘要

Novel gamma-[Glu]((n >= 1))-Gln-Ca chelates were prepared by using gamma-[Glu]((n >= 1))-Gln (mixture peptides containg gamma-Glu-Gln, gamma-Glu-Glu-Gln, gamma-Glu-Glu-Glu-Gln, gamma-Glu-Glu-Glu-Glu-Gln, gamma-Glu-Glu-Glu-Glu-Glu-G1n) which were synthesized by glutaminase. Based on single factor and orthogonal array experiments, the optimal calcium-chelation conditions were as follows: 30 min chelation at 70 degrees C; peptide concentration, 0.15 g/mL; mixture peptides-tocalcium mass ratio, 25:1. The particle size of chelates was 743.6 +/-( )64.2 nm and the chelates appeared stable neutral molecular entities with 91.33% of chelation rate and 35.2 mg/g of calcium, also with higher thermostability. Chelated calcium ions might be surrounded by coordination bonds linking to two or more connecting points: oxygen atoms (carboxyl oxygen, hydroxyl oxygen and oxygen of peptide bonds) and nitrogen atoms (amino nitrogen). The chelates could be used for food/nutraceutical applications, as no toxicity at 0.125-10 mg/mL and enhanced efficiency in calcium release (releasing percentage over 85% at pH 8.0), transport and uptake compared with CaCl2 were detected in Caco-2 cells.

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