Detection of low molecular weight copper(II) and zinc(II) binding ligands in ultrafiltered milks—the citrate connection

EFFECTIVENESS of ORGANIC CHELATORS IN SOLUBILIZING CALCIUM AND ZINC IN FORTIFIED CEREALS UNDER SIMULATED GASTROINTESTINAL pH CONDITIONS

“…Citric acid is a known chelator of divalent cations. Recent research has suggested that citric acid, in its capacity as a low molecular weight zinc-binding ligand, could be responsible for the efficient absorption of zinc from human milk (Casey et al 1981;Martin et al 1981;Fransson and Lonnerdal 1982;Hurley and Lonnerdal 1982). In this study, where citric acid was complexed with zinc prior to addition to calcium supplemented wheat cereals, the solubility of both zinc and calcium was enhanced (P < 0.05) at citric acid to zinc molar ratios of 10: 1 or greater at the end of a simulated gastrointestinal sequential pH adjustment (Fig.…”

Zinc binding properties of human prostatic tissue, prostatic secretion and seminal fluid

“…This is present in prostatic fluid in a 10-fold molar excess over zinc and both co-eluted from a G-15 Sephadex column. The major zinc-binding molecule of low Mr in human milk is also thought to be citrate (Lonnerdal, Stanislowski & Hurley, 1980;Martin, Licklider, Bushmiller & Jacobs, 1981;Arver, 1982b).…”

Distribution of Trace Elements and Minerals in Human and Cow's Milk

“…A high binding constant of a LMW ligand can cause less zinc to be bound to proteins which may inhibit absorption (16,20). Although the identification of the LMW ligand in human milk has been controversial (1 9), the initial report of citrate being this ligand has been verified by several other investigators (1,3,26). The presence or zinc-binding properties in milk of other suggested ligands, such as picolinic acid (9), has not been confirmed outside the laboratories of their initial report.…”