Zinc binding in cow's milk and human milk.
نویسندگان
چکیده
In both cow's milk and human milk, zinc was associated with proteins of high molecular weight (greater than 100 000), as judged by analysis with Sephadex G-75. Precipitation of the casein at pH 4.6 and filtration of the resultant acid whey on Sephadex G-25 led, however, to the recovery of about 90% of the zinc as a compound of low molecular weight, which was tentatively identified as zinc citrate. Over 95% of the zinc of cow's milk was sedimented with the casein micelles on ultracentrifugation. Filtration of these micellar caseins on Sephadex G-150 gave two peaks containing zinc, which corresponded to aggregates of alpha-casein-kappa-casein and of alpha-casein-beta-casein. Ultracentrifugation of human milk sedimented only approx. 40% of total zinc. Analysis of sediment and supernatant on Sephadex G-150, however, indicated that about 85% of the zinc was associated with a protein complex of molecular weight greater than 150 000. The major protein of this complex was identified as lactoferrin. A minor zinc-binding component of average molecular weight 30 000 was also observed in the supernatant. The results indicated that zinc is bound to different macromolecules in cow's and human milk. This may be a factor affecting the bioavailability to the human infant of zinc from the two milks, and it is suggested that in human milk lactoferrin may be involved in the uptake of zinc.
منابع مشابه
Changes in zinc in milk during enzymatic digestion.
Zinc is known to be an essential element for human nutrition and good health1). Milk is its sole source in infants, and growing children as well as mature adults consume varying amounts of milk, which provide them with much of the needed zinc. Investigators, using gel filtration chromatography2,3), have demonstrated that zinc in cow's milk can be associated with fractions of high molecular weig...
متن کاملCow's Milk Protein Allergy Mimicking Acrodermatitis Enteropathica.
Cow's milk protein allergy is an adverse immune reaction to one or more of the constituent proteins of milk obtained from any animal, most commonly alpha s 1-casein cow's milk. In many cases, the allergy is genetic in origin. The infants may experience symptoms within minutes after feeding (rapid onset) or commonly after 7-10 days of consuming the cow's milk (slower onset). Many children with c...
متن کاملDigestion of the zinc in human milk, cow's milk and a commercial babyfood: some implications for human infant nutrition.
1. The digestion of zinc present in human milk, cow's milk and a commercial babyfood was compared, using the piglet as a model for the human infant. 2. In piglets given human milk the pH of stomach contents was approximately 1 and 0.4 units lower than that of animals given respectively cow's milk and babyfood. The pH values of intestinal contents were approximately neutral and did not vary with...
متن کاملFortifying milk with ferrous gluconate and zinc oxide in a public nutrition program reduced the prevalence of anemia in toddlers.
We aimed to assess the efficacy of whole cow's milk fortified with ferrous gluconate and zinc oxide, along with ascorbic acid, in reducing the prevalence of anemia and improving iron status of low income children 10-30 mo of age. Healthy children were randomly assigned to drink 400 mL/d of cow's whole milk, either fortified milk (FM) with 5.8 mg/400 mL of iron as ferrous gluconate, 5.28 mg/400 ...
متن کاملRabbit antibodies against the folate binding protein from cow's milk. Production, characterization and use for development of an enzyme-linked immunosorbent assay (ELISA).
Rabbit antibodies to purified folate binding protein from cow's milk whey were used for development of a two-site enzyme-linked immunosorbent assay (ELISA) for quantitation of bovine folate binding proteins. The folate binding proteins in human milk and serum showed no cross-reactivity. A partial saturation of purified bovine folate binder with folate gave rise to an increased antigenicity prob...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Biochemical journal
دوره 209 2 شماره
صفحات -
تاریخ انتشار 1983