Tryptic phosphopeptides from whole casein. II. Physicochemical properties related to the solubilization of calcium

Abstract

SUMMARY. Casein phosphopeptides (CPP) were produced by tryptic hydrolysis of sodium caseinate and further purified by precipitation and chromatography on QAE-Sephadex A-25. Their physico-chemical properties were compared with the properties of an enzymically dephosphorylated equivalent preparation (DPP). Binding of Ca 2+ to the peptides was measured using a Ca selective electrode and was found to increase with pH and to show 1/1 stoicheiometry Ca/P org in CPP at pH 6 -5 a.nd 7-6. Klotz plots indicated equivalent binding sites at these two pH values, but some heterogeneity was seen at pH 3-5. In contrast, DPP did not bind significant amounts of Ca 2+ . CPP effectively inhibited the formation of insoluble calcium phosphates at different Ca/P ratios. The effective CPP concentration was 10 mg/1 and complete stability of calcium phosphate solutions was obtained at about 100 mg/1. This stabilizing effect was dependent on the presence of organic P.

Zinc Transport in Caco-2 Cells and Zinc Balance in Rats: Influence of the Heat Treatment of a Casein−Glucose−Fructose Mixture

“…Assays with Caco-2 cells have shown that the addition of certain casein phosphopeptides (CPP-Ca) at levels higher than 14 µmol/L depressed Zn binding plus uptake (Hansen et al, 1996). Because CPP can be formed in vitro by pepsin digestion of casein (Berrocal et al, 1989), the decrease in Zn uptake found in the present assays may also be due to the presence of similar compounds.…”

Caseins as source of bioactive peptides

“…Milk and dairy products provide plenty of Ca 2+ , which can form soluble complexes with those phosphopeptides, thus avoiding Ca phosphate precipitation (Sato, Naguchi, & Naito, 1986;Berrocal et al, 1989), and enhancing intestinal absorption of Ca and retention thereof in the body (Mykk. anen & Wasserman, 1980;Sato et al, 1986).…”

Complexation du fer par le phosphopeptide (1-25) de la caséine β : action de l'alcalase et de la phosphatase acide

“…Les différents récepteurs caséini-ques étudiés étaient les caséines totales (Harzer et Kauer, 1982), les caséines individuelles (Brulé et Fauquant, 1982;Baumy et al, 1989) et les CPP (Brulé et al, 1980;Berrocal et al, 1989). Il ressort de ces études que la capacité ainsi que l'affinité des CPP pour les cations dépendent à la fois du degré de phosphorylation des caséines (as > 13 > K) et du cation utilisé (Demott et Dincer, 1976;Lonnerdal et al, 1985).…”