Isolation and Characterization of Sheep Lactoferrin, an Inhibitor of Platelet Aggregation and Comparison with Human Lactoferrin

Highly purified sheep lactoferrin was isolated from ovine whey in a single chromatographic step (FPLC): it was characterized by electrophoresis, N-terminal sequence determination and compared with lactoferrins from other species. Sheep and human lactoferrins inhibited thrombin-induced platelet aggregation (median inhibitory concentration: IC50 5 and 4 microM, respectively). Pepsin hydrolysates of human and sheep lactoferrins were fractionated by reverse-phase high-performance liquid chromatography and only one peak was an inhibitor of platelet aggregation. The sheep or human lactoferrin binding to platelets was studied.