Ward P P, Chu H, Zhou X, Conneely O M
Department of Cell Biology, Baylor College of Medicine, Houston, TX 77030, USA.
Gene. 1997 Dec 19;204(1-2):171-6. doi: 10.1016/s0378-1119(97)00539-8.
Lactoferrin (Mw=78 kDa) is a member of the transferrin family of iron-binding glycoproteins. Previous studies carried out primarily in vitro indicate that the protein has multifunctional properties and may be involved in regulation of iron homeostasis, inhibition of bacterial growth and regulation of immune responses. However, the significance and species specificity of these proposed functions in vivo have not been adequately addressed due to lack of sufficient purified homospecies lactoferrin for analysis in small animal models. We previously reported the successful production of biologically active recombinant human lactoferrin using an Aspergillus expression system. In the present study, we report the production of recombinant murine lactoferrin using a similar expression strategy. Recombinant murine lactoferrin was purified to homogeneity and was similar in size and immunoreactivity to native murine milk lactoferrin. The recombinant protein was correctly processed at its N-terminus and was glycosylated. Interestingly, while both human and murine lactoferrin bind iron in a 2:1 molar ratio, iron bound to recombinant murine lactoferrin was more acid labile than human lactoferrin, demonstrating species-specific variation in the stability of iron-binding to this protein. Finally, the availability of recombinant murine lactoferrin will now facilitate the study of the species specificity of lactoferrin action in a mouse model system.
乳铁蛋白（分子量=78 kDa）是铁结合糖蛋白转铁蛋白家族的一员。此前主要在体外进行的研究表明，该蛋白具有多种功能特性，可能参与铁稳态的调节、细菌生长的抑制以及免疫反应的调节。然而，由于缺乏足够的纯化同种乳铁蛋白用于在小动物模型中进行分析，这些假定功能在体内的重要性和物种特异性尚未得到充分探讨。我们之前报道了使用曲霉表达系统成功生产具有生物活性的重组人乳铁蛋白。在本研究中，我们报道了使用类似的表达策略生产重组鼠乳铁蛋白。重组鼠乳铁蛋白被纯化至同质，其大小和免疫反应性与天然鼠乳乳铁蛋白相似。重组蛋白在其N端得到正确加工且进行了糖基化。有趣的是，虽然人和鼠乳铁蛋白均以2:1的摩尔比结合铁，但与重组鼠乳铁蛋白结合的铁比人乳铁蛋白的铁更易被酸破坏，这表明该蛋白在铁结合稳定性方面存在物种特异性差异。最后，重组鼠乳铁蛋白的可得性将有助于在小鼠模型系统中研究乳铁蛋白作用的物种特异性。
