Abstract
Properties of iron-saturated and iron-free lactoferrins from bovine and human milk were compared after digestion in vitro with pepsin at pH 4.5 for 2h followed by trypsin at pH 7.5 for 3h. After digestion, the percentage of 6% TCA-soluble nitrogen, the residual iron-binding capacity, and immunological reactivity were, respectively, 6.0%, 85.0%, and 100% for iron-saturated human lactoferrin, 32.0%, 44.4% and 62.9% for iron-free human lactoferrin, 5.2%, 82.8% and 89.5% for iron-saturated bovine lactoferrin and 35.0%, 39.5% and 34.7% for iron-free bovine lactoferrin. Disc gel electrophoretic and immunoelectrophoretic patterns differed between iron-free lactoferrins from human and bovine milk after the digestion. Bacteriostatic activity against E. coli 0111 was not observed in ironsaturated lactoferrins from human or bovine milk. Iron-free lactoferrins from human or bovine milk retained bacteriostatic activity after digestion with pepsin and trypsin, but this activity decreased with prolonged digestion.
