LACTOFERRIN BINDING ACTIVITY IN TRITRICHOMONAS FOETUS

胎儿三毛滴虫是一种重要的原生动物寄生虫 牛阴道 据了解，这种寄生虫可以利用 乳铁蛋白作为铁的来源。 其他人已经证明了这一点 乳铁蛋白-胶体金结合物 内化到寄生虫体内 然而，生物化学机制 的约束力还没有得到很好的理解。 由于乳铁蛋白是一种非常基本的 蛋白质，目前还不清楚是否结合到寄生虫是由于 静电荷相互作用和/或需要特定受体。 我们已经检查了放射性标记的胎儿三毛滴虫的结合 蛋白质转化为乳铁蛋白， 不带电荷的多肽。 放射性标记的寄生虫裂解， 洗涤剂和用乳铁蛋白-琼脂糖孵育的裂解物。 后 广泛洗涤后，将特异性结合的蛋白质从 乳铁蛋白-琼脂糖凝胶，使用低pH缓冲液， 中和 放射性标记的蛋白质然后反弹回 乳铁蛋白-琼脂糖凝胶，存在乳铁蛋白或聚氨基 acids. 与乳铁蛋白的再结合被 乳铁蛋白 带电荷的聚氨基酸如聚赖氨酸和 聚谷氨酸确实以剂量依赖性方式抑制再结合， 这种抑制不大于使用 乳铁蛋白作为抑制剂。 相比之下，聚甘氨酸没有 在任何浓度下对结合的抑制作用。 综合起来看， 这些数据表明，表面上的结合粘附素， 寄生虫，特异性结合乳铁蛋白

Tritrichomonas foetus is an important protozoan parasite of the bovine vaginal tract. It is known that this parasite can use lactoferrin as a source of iron. It has been demonstrated by others that lactoferrin-colloidal gold conjugates bind to and are internalized into the parasite. However, the biochemical mechanisms of binding are not well understood. Since lactoferrin is a very basic protein, it is unclear whether binding to the parasite is due to electrostatic charge interactions and/or requires specific receptors. We have examined the binding of radiolabeled Tritrichomonas foetus proteins to lactoferrin in the presence of various charged and uncharged polypeptides. Radiolabeled parasites were lysed in detergent and the lysates incubated with lactoferrin-Sepharose. After extensive washes, the specifically bound proteins were eluted off the lactoferrin-Sepharose using a low pH buffer followed by neutralization. The radiolabeled proteins were then rebound back to lactoferrin-Sepharose in the presence of lactoferrin or poly-amino acids. The rebinding to lactoferrin was strongly inhibited by lactoferrin. Charged poly-amino acids such as poly-lysine and poly-glutamate did inhibit rebinding in a dose-dependent manner but this inhibition was no greater than 30-40% of that observed using lactoferrin as an inhibitor. In contrast, poly-glycine had no inhibitory effect on binding at any concentration. Taken together, the data suggest that the binding adhesins on the surface of the parasite, specifically bind to lactoferrin