Laboratory of Veterinary Biochemistry, School of Veterinary Medicine, Kitasato University, Towada, Aomori, 034-8628, Japan.
Biometals. 2012 Oct;25(5):1083-8. doi: 10.1007/s10534-012-9573-3. Epub 2012 Jul 24.
Bovine milk α-casein has been identified as an iron- and heme-binding protein. However, the physiological role of its iron-binding remains to be elucidated in more detail. α-Casein was immobilized on CNBr-activated Sepharose 4B beads, and the α-casein agarose beads efficiently bound hemin as well as ferrous ammonium sulfate (Fe(2+)) as compared with control beads. Additionally, α-casein-beads bound bovine holo-lactoferrin (Lf), but not holo-transferrin. Lf caused the release of Fe(2+) which had bound to the α-casein-agarose beads beforehand. These results suggest that bovine α-casein iron-dependently binds holo-bovine Lf more strongly than Fe(2+), and that strong binding between them may play a physiological role in regulating iron homeostasis in the bovine mammary gland.
牛奶α-酪蛋白已被鉴定为一种铁和血红素结合蛋白。然而，其铁结合的生理作用仍有待更详细地阐明。α-酪蛋白固定在 CNBr 活化的 Sepharose 4B 珠上，与对照珠相比，α-酪蛋白琼脂糖珠能够有效地结合血红素和硫酸亚铁铵（Fe(2+)）。此外，α-酪蛋白珠结合牛全乳糖结合乳铁蛋白（Lf），但不结合全转铁蛋白。Lf 导致先前与α-酪蛋白琼脂糖珠结合的 Fe(2+)释放。这些结果表明，牛α-酪蛋白铁依赖性地比 Fe(2+)更强烈地结合牛全乳糖结合乳铁蛋白，它们之间的强结合可能在调节牛乳腺中的铁稳态方面发挥生理作用。
