Evans G W, Johnson P E
Pediatr Res. 1980 Jul;14(7):876-80. doi: 10.1203/00006450-198007000-00007.
A low-molecular-weight zinc-binding ligand from human milk has been isolated and characterized. The ligand was isolated by chromatography on Dowex 50, Dowex 1, and Sephadex G-15 equilibrated with 0.153 mM Zn(NO3)2. Mass spectroscopy, thin-layer chromatography, and infrared spectroscopy proved that the zinc-binding ligand isolated by this method from human milk is pyridine-2-carboxylic acid, commonly known as picolinic acid. The concentration of picolinic acid in human milk was 308 microM, the concentration in one brand of processed cow's milk was 20 microM, but picolinic acid was undetectable in a second brand of cow's milk and in four different infant formulas. Weanling rats fed supplemental picolinic acid absorbed significantly more dietary zinc and gained significantly more weight than rats fed an unsupplemented diet. The results suggest that the high bioavailability of zinc in human milk results from the presence of picolinic acid, a bidentate chelating ligand which facilitates zinc absorption from the intestine.
一种来自人乳的低分子量锌结合配体已被分离和鉴定。该配体通过在Dowex 50、Dowex 1和用0.153 mM硝酸锌平衡的Sephadex G - 15上进行色谱分离而得到。质谱分析、薄层色谱分析和红外光谱分析证明，通过这种方法从人乳中分离出的锌结合配体是吡啶 - 2 - 羧酸，通常称为皮考林酸。人乳中皮考林酸的浓度为308微摩尔，一种品牌的加工牛奶中浓度为20微摩尔，但在另一种品牌的牛奶和四种不同的婴儿配方奶粉中未检测到皮考林酸。喂食补充皮考林酸的断奶大鼠比喂食未补充饮食的大鼠吸收的膳食锌显著更多，体重增加也显著更多。结果表明，人乳中锌的高生物利用度源于皮考林酸的存在，皮考林酸是一种双齿螯合配体，有助于锌从肠道吸收。
