Lactoferrin (LF) is an Fe3+ -binding glycoprotein first recognized in milk and then in other epithelial secretions and barrier body fluids to which many different functions have been attributed to LF, including protection from iron-induced lipid peroxidation, immunomodulation, cell growth regulation, DNA and RNA binding, as well as transcriptional activation, еtс. The polyfunctional physiological role of LF is still unclear, but it has been suggested to be responsible for primary defense against microbial and viral infections. Here, we present the first evidence that LF preparations isolated from milk of 18 cows of different breeds possess various levels of metal-dependent DNase and metal-independent RNase activities. For univocal assignment of DNase and RNase activities to cow LF, it was subjected to SDS-PAGE using gels with copolymerized calf thymus DNA or polymeric yeast RNA. In situ analysis was revealed DNase and RNase activities only in the gel zones corresponding to homogeneous LF. In contrast to human LF, cow LF possesses a relatively low cytotoxicity towards human tumor cells. The discovery that cow LF has these activities may contribute to understanding the multiple physiological functions of this extremely polyfunctional protein, including its protective role against microbial and viral infections. The computational spatial model of cow LF complex with DNA was obtained: according to the model positively charged residues of LF contact with DNA.

中文翻译：

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新鲜牛奶乳铁蛋白的DNase和RNase活性。

乳铁蛋白（LF）是一种与Fe3 +结合的糖蛋白，首先在牛奶中被发现，然后在其他上皮分泌物和屏障体液中被识别，LF具有许多不同的功能，包括防止铁诱导的脂质过氧化，免疫调节，细胞生长调节， DNA和RNA的结合以及转录激活。LF的多功能生理学作用仍不清楚，但已被认为是抵抗微生物和病毒感染的主要防御因素。在这里，我们提供的第一个证据是，从不同品种的18头奶牛的牛奶中分离的LF制剂具有不同水平的金属依赖性DNase和金属依赖性RNase活性。为了将DNase和RNase活性明确分配给母牛LF，使用带有共聚的小牛胸腺DNA或聚合酵母RNA的凝胶对它进行SDS-PAGE。原位分析显示，DNase和RNase活性仅在对应于均质LF的凝胶区中。与人LF相反，牛LF对人肿瘤细胞具有相对较低的细胞毒性。牛LF具有这些活性的发现可能有助于理解这种极其多功能的蛋白质的多种生理功能，包括其对微生物和病毒感染的保护作用。得到了带有DNA的牛LF复合物的计算空间模型：根据该模型，LF与DNA接触的带正电荷的残基。牛LF对人肿瘤细胞具有相对较低的细胞毒性。牛LF具有这些活性的发现可能有助于理解这种极其多功能的蛋白质的多种生理功能，包括其对微生物和病毒感染的保护作用。得到了带有DNA的牛LF复合物的计算空间模型：根据该模型，LF与DNA接触的带正电荷的残基。牛LF对人肿瘤细胞具有相对较低的细胞毒性。牛LF具有这些活性的发现可能有助于理解这种极其多功能的蛋白质的多种生理功能，包括其对微生物和病毒感染的保护作用。得到了带有DNA的牛LF复合物的计算空间模型：根据该模型，LF与DNA接触的带正电荷的残基。