The University of Queensland, School of Agriculture and Food Sciences, Brisbane, QLD 4072, Australia.
Food Chem. 2013 Dec 1;141(3):3007-13. doi: 10.1016/j.foodchem.2013.05.139. Epub 2013 Jun 7.
Three forms of bovine lactoferrin (Lf), apo-, native- and holo- with 0.9%, 12.9% and 99.7% iron content, respectively, were characterised for their physico-chemical properties. Colour, surface tension, thermal properties, particle charge and rheological behaviour of Lf were found to be affected by the form of Lf. The surface tension of Lf tends to decrease with decrease in iron content. The Circular Dichroism (CD) spectra confirmed that all forms of Lf had similar secondary structures while the tertiary structure was different for holo-Lf. The Differential Scanning Calorimeter (DSC) analysis showed that the apo- and holo-Lf in aqueous solution displayed thermal denaturation temperatures of 71±0.2 and 91±0.5 °C, respectively, suggesting that the iron saturation of Lf tends to increase its thermal stability. The study of particle charge properties (ζ-potential) in 1 mM KCl salt solution showed that apo-Lf reached the net charge of zero in the pH range 5.5-6.5 whereas native and holo-Lf in the pH range 8.0-9.0. The apparent viscosity of 1% (wt/wt) solution of the different forms of Lf showed no difference between apo- and native-Lf (≈1.4 mPas) while the value was significantly higher (2.38 mPas) for holo-Lf.
三种牛乳铁蛋白（Lf）形式，即脱铁、天然和全铁，分别具有 0.9%、12.9%和 99.7%的铁含量，其理化性质特征如下。Lf 的颜色、表面张力、热性质、颗粒电荷和流变行为均受到 Lf 形式的影响。Lf 的表面张力随着铁含量的降低而降低。圆二色性（CD）光谱证实，所有形式的 Lf 均具有相似的二级结构，而全铁 Lf 的三级结构则不同。差示扫描量热仪（DSC）分析表明，水相中的脱铁和全铁 Lf 的热变性温度分别为 71±0.2 和 91±0.5°C，表明 Lf 的铁饱和程度趋于增加其热稳定性。在 1mM KCl 盐溶液中研究颗粒电荷特性（ζ-电位）表明，脱铁 Lf 在 pH 5.5-6.5 范围内达到零净电荷，而天然和全铁 Lf 在 pH 8.0-9.0 范围内达到零净电荷。不同形式 Lf 的 1%（wt/wt）溶液的表观粘度在脱铁和天然 Lf 之间没有差异（≈1.4 mPas），而全铁 Lf 的值明显更高（2.38 mPas）。
