Brock J H, Arzabe F, Lampreave F, Piñeiro A
Biochim Biophys Acta. 1976 Sep 28;446(1):214-25. doi: 10.1016/0005-2795(76)90112-4.
The iron-saturated and iron-free (apo) forms of bovine transferrin and lactoferrin were digested with trypsin and the digests analysed by column chromatography and electrophoresis. Both of the iron-saturated proteins were more resistant to proteolysis than the corresponding apoproteins, and iron-transferrin was more resistant than iron-lactoferrin. Digestion of iron-transferrin yielded two iron-binding fragments with molecular weights of 32 000 and 38 500 whereas apotransferrin yielded only the larger fragment. In digests of lactoferrin, up to five different fragments with molecular weights ranging from 25 000 to 52 700 were detected, there being no obvious qualitative difference between digests of iron-lactoferrin and apolactoferrin. The susceptibility of apolactoferrin to tryptic digestion was only slightly reduced when apolactoferrin was complexed with beta-lactoglobulin, suggesting that complex-formation is not a mechanism for protecting lactoferrin against intestinal degradation. There was no immunological cross reaction between bovine transferrin or its digestion products against anti-lactoferrin antiserum, or vice-versa.
用胰蛋白酶消化牛转铁蛋白和乳铁蛋白的铁饱和形式及脱铁（脱辅基）形式，并通过柱色谱和电泳分析消化产物。两种铁饱和蛋白比相应的脱辅基蛋白更抗蛋白水解，且转铁蛋白比乳铁蛋白更抗水解。铁转铁蛋白消化产生两个分子量分别为32000和38500的铁结合片段，而脱铁转铁蛋白只产生较大的片段。在乳铁蛋白的消化产物中，检测到多达五个分子量在25000至52700之间的不同片段，铁乳铁蛋白和脱铁乳铁蛋白的消化产物之间没有明显的定性差异。当脱铁乳铁蛋白与β-乳球蛋白复合时，其对胰蛋白酶消化的敏感性仅略有降低，这表明形成复合物不是保护乳铁蛋白免受肠道降解的机制。牛转铁蛋白或其消化产物与抗乳铁蛋白抗血清之间没有免疫交叉反应，反之亦然。
